THE  UNIVERSITY 
OF  ILLINOIS  V 
LIBRARY 


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GEOLOGY 


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MAY  2  o  1344 


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JfiN  5  .  1981 


CONTRIBUTIONS  TO  THE  GEOLOGY  AND  PALAEONTOLOGY 

OF  THE  WEST  INDIES. 


MIOCENE  MOLLUSKS  FROM  BOWDEN  JAMAICA. 


’  \\\Y 

WENDELL  P.  WOODRING. 


Published  by  the  Carnegie  Institution  of  Washington 

Washington,  May  1925 


CARNEGIE  INSTITUTION  OF  WASHINGTON 


Publication  No.  366 


liopies  <)t  this  hock 

MAY  2  0  1925 

--  r  -  — - - 


JUDD  &  DETWEILER,  INC., 
WASHINGTON,  D.  C. 


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CONTENTS. 


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Introduction .  1 

Marine  Tertiary  deposits  of  Jamaica .  .  4 

Eocene .  4 

Oligocene .  5 

Miocene .  6 

Pliocene .  6 

Bowden  formation .  7 

Source  of  data .  7 

Name,  type  locality,  and  distribution  7 

Lithology,  structure,  and  thickness.  7 

Stratigraphic  relations .  8 

Fossils .  8 

Age .  8 

Previous  reports .  9 

Description  of  species .  13 

Nuculidae .  13 

Nucula  (Nucula)  morantensis.  ...  13 

Nucula  (Nuculopsis)  hilli .  14 

Ledidae . .  15 

Leda  (Saccella)  peltella .  16 

Leda  (Saccella)  subcerata .  17 

Leda  (Saccella)  indigena .  17 

Leda  (Jupiteria)  bowdenensis 

bowdenensis .  19 

Leda  (Jupiteria)  bowdenensis  sub- 

tumida .  19 

Leda  (Jupiteria)  duerdeni .  19 

Leda  (Pseudoportlandia)  clara ....  20 

Yoldia  (Orthoyoldia)  ovalis .  22 

Malletiidae .  23 

Tindaria  (Tindaria)  species .  23 

Arcidae . 24 

Glycymeris  (Glycymeris)  jamai- 

censis .  24 

Glycymeris  (Glycymeris)  acuticos- 

tata  plasia .  25 

Glycymeris  (Glycymerella)  prepen- 

nacea .  27 

Area  (Area)  occidentalis .  29 

Area  (Area)  umbonata  morantensis  30 

Area  (Area)  bowdeniana .  31 

Area  (Area)  yaquensis  berryi .  32 

Barbatia  (Barbatia)  islopa .  34 

Barbatia  (Barbatia)  propertua. ...  34 

Barbatia  (Barbatia)  delepida .  34 

Barbatia  (Barbatia)  endomena. ...  35 

Barbatia  (Barbatia)  inusitata .  35 

Barbatia  (Acar)  domingensis .  37 


Barbatia  (Obliquarca)  dentera ....  39 

Barbatia  (Obliquarca)  subcandida  39 
Barbatia  (Obliquarca)  modiolida..  40 
Barbatia  (Diluvarca)  halidonata 


halidonata . 42 

Barbatia  (Diluvarca)  halidonata 

oresta .  43 

Barbatia  (Diluvarca)  perplura. ...  44 

Barbatia  (Diluvarca)  prephaina. . .  44 

Barbatia  (Diluvarca)  inaequilat- 

eralis .  45 

Barbatia  (Diluvarca)  dasia .  46 

Barbatia  (Diluvarca)  wordeni ....  46 

Barbatia  (Diluvarca)  agnastha. ...  47 


PAGE 


Description  of  species — Cont. 

Arcidae — Cont. 

Barbatia  (Diluvarca)  thomasensis.  48 

Barbatia  (Diluvarca)  donacia .  48 

Barbatia  (Diluvarca)  microtera. . .  49 

Barbatia  (Diluvarca)  ophthanta . .  50 

Fossularca  (Fossularca)  adamsi 

sawkinsi .  51 

Fossularca  (Ovalarca)  ovalina ....  52 

Bathyarca  hendersoni .  53 

Limopsidae .  54 

Limposis  (Pectunculina)  ovalis 

silova .  55 

Limopsis  (Pectunculina)  jamai- 

censis .  55 

Pinnidae .  56 

Pinna  refurca .  56 

Atrina  species .  57 

Isognomonidae .  57 

Isognomon  species .  58 

Pteriidae .  58 

Pteria  inornata .  58 

Ostreidae .  59 

Ostrea  (Lopha)  paramegodon .  60 

Ostrea  (Lopha)  guppyi .  61 

Ostrea  (Lopha)  folioides .  61 

Pectinidae . . .  62 

Pecten  (Pecten)  barretti .  62 

Pecten  (Euvola)  bowdenensis .  63 

Chlamys  (Chlamys)  species .  65 

Chlamys  (Chlamys)  vaginulus ....  65 

Chlamys  (Chlamys)  bellipictus.  .  .  66 

Chlamys  (Aequipecten)  plurino- 

minis  morantensis .  67 

Chlamys  (Plagioctenium)  uselmae  69 
Chlamys  (Plagioctenium)  concin- 

natus .  70 

Chlamys  (Plagioctenium)  ameleus  70 
Chlamys  (Plagioctenium)  mans- 

fieldi .  71 

Chlamys  (Plagioctenium)  gonioides  71 

Chlamys  (Palliolum?)  guppyi .  72 

Amusium  (Amusium)  papyra- 

ceum? .  73 

Amusium  (Parvamussium)  spen- 

dulum .  75 

Spondylidae .  75 

Spondylus  bostrychites .  76 

Spondylus  species .  77 

Plicatula  guppyi .  78 

Limidae .  79 

Lima  (Lima)  stenacostata .  79 

Lima  (Mantellum)  species .  80 

Limea  solida .  81 

Anomiidae .  82 

Placunanomia  lithobleta .  82 

Anomia  indecisa . . . .  84 

Mytilidae . .  84 

Modiolus  (Brachydontes)  guppyi..  85 

Dreissenidae .  86 

Mytilopsis  jamaicensis .  86 

in 


IV 


CONTENTS. 


PAGE 


Description  of  species — Cont. 

Juliidae .  87 

Julia  gardnerae .  88 

Poromyacidae .  88 

Poromya  jamaicensis .  88 

Cuspidariidae .  89 

Cuspidaria  (Cardiomya)  craspe- 

donia . 90 

Cuspidaria  (Bowdenia)  distira. ...  91 

Verticordiidae .  91 

Verticordia  (Trigonulina)  bowden- 

ensis . 92 

Verticordia  (Haliris)  jamaicensis.  93 

Crassatellitidae . .  .  .  .  93 

Crassatellites  (Crassatellites)  jam¬ 
aicensis  .  94 

Crassatellites  (Crassatellites)  alta- 

spissus .  95 

Crassinella  guppyi .  96 

Crassinella  bowdenensis .  97 

Crassinella  xena .  98 

Carditidae .  98 

Cardita  (Gians)  scabricostata .  ...  99 

Venericardia  (Pleuromeris)  acaris.  102 

Chamidae .  102 

Chama  involuta .  103 

Chama  macerophylla .  104 

Echinochama  antiquata .  106 

Lucinidae .  107 

Codakia  (Codalda)  spinulosa .  108 

Codakia  (Codakia)  lomonea .  108 

Codakia  (Jagonia)  vendryesi .  109 

Codakia  (Jagonia)  guppyi .  110 

Lucina  (Lucina)  bowdenensis .  Ill 

Myrtaea  (Myrtaea)  limoniana. ...  112 
Myrtaea  (Myrteopsis)  pertenera. .  113 
Myrtaea  (Eulopia)  vermiculata. . .  114 

Myrtaea  (Eulopia)  furcata .  115 

Miltha  (Megaxinus)  gluminda.  ...  117 
Phacoides  (Phacoides?)  species....  117 
Phacoides  (Linga)  podagrinus 

podagrinus .  119 

Phacoides  (Linga)  podagrinus  alar- 

antus .  119 

Phacoides  (Linga)  browni .  120 

Phacoides  (Linga)  tithonis .  120 

Phacoides  (Pleurolucina)  quadri- 

costatus .  121 

Phacoides  (Cardiolucina)  recur- 

rens . 122 

Phacoides  (Callucina)  pauperatus 

pauperatus .  123 

Phacoides  (Callucina)  pauperatus 

oligocostatus .  124 

Phacoides  (Callucina)  eurycostatus  124 
Phacoides  (Parvilucina)  yaquensis 

morantensis .  125 

Phacoides  (Parvilucina)  limnidus.  126 
Phacoides  (Bellucina)  actinus.  . .  .  126 
Divaricella  (Divaricella)  prevari- 

eata .  128 

Diplodontidae .  128 

Diplodonta  (Diplodonta)  walli .  .  .  129 
Diplodonta  (Diplodonta)  homalo- 

striata .  129 

Diplodonta  (Felaniella  )minor. . . .  130 


Diplodonta  (Phlyctiderma)  gabbi.  131 


PAGE 


Description  of  species — Cont. 

Eryeinidae . 

Erycina  (Erycina)  olssoni . 

Erycina  (Erycina)  pura . 

Sportellidae? . 

Neaeromya  menotreta . 

Cardiidae . 

Cardium  (Acanthocardia?)  dis- 

sidepictum . 

Cardium  (Trachycardium)  lingu- 

ualeonsis . 

Cardium  (Trachycardium)  bow- 

denense . 

Cardium  (Trachycardium)  incon- 

spicuum . 

Cardium  (Trachycardium)  way- 

landi . 

Cardium  (Fragum)  medium . 

Cardium  (Fragum)  elattocostatum 
Cardium  (Trigoniocardia)  haitense 

haitense . 

Cardium  (Trigoniocardia)  haitense 

cercadicum . 

Cardium  (Trigoniocardia)  thau- 

mastum . 

Cardium  (Laevicardium)  serratum 
Protocardia  (Nemocardium)  ja¬ 
maicensis  . 

Pliocardiidae . 

Pliocardia  bowdeniana . 

Veneridae . 

Tivela  (Tivela)  jamaicensis . 

Gafrarium  (Gouldia)  insulare . 

Callocardia  (Callocardia)  ammon- 

dea . 

Callocardia  (Callocardia)  elethusa. 
Pitar  (Hyphantosoma)  carbaseus. . 
Pitar  (Hysteroconcha)  planivietus 
Antigona  (Ventricola)  blandiana.. 

Cyclinella  plasiatenius . 

Chione  (Chione)  sawkinsi . 

Chione  (Chione)  woodwardi . 

Chione  (Chione)  retugida . 

Chione  (Lirophora)  hendersoni .  .  . 

Parastarte  antillensis . 

Cooperellidae . 

Cooperella  (Cooperellopsis)  thau- 

masta . 

Tellinidae . . . 

Tellina  (Moerella)  simpsoni . 

Tellina  (Moerella)  hendersoni .... 

Tellina  (Eurytellina)  species . 

Tellina  (Eurytellina)  spiekeri . 

Tellina  (Eurytellina)  pharcida. . .  . 

Tellina  (Eurytellina)  gonida . 

Tellina  (Eurytellina)  halistrepta. . 

Tellina  (Eurytellina)  apomsa . 

Tellina  (Eurytellina)  browni . 

Tellina  (Merisca)  species . 

Tellina  (Merisca)  sclera  sclera .... 
Tellina  (Merisca)  sclera  lerasca. . . 

Tellina  (Mersica)  acrocosmia . 

Tellina  (Scissula)  healyi . 

Tellina  (Elliptotellina)  cymobia. . . 

Strigilla  (Strigilla)  pisiformis . 

Macoma  (Psammacoma)  tracta... 
Macoma  (Psammacoma)  olivella . . 


132 

132 

133 
133 

133 

134 

135 

136 

137 

138 

139 

140 

141 

142 

143 

144 

145 

147 

147 

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148 

149 

150 

151 

152 

153 
155 

157 

158 

159 

160 
161 

163 

164 

165 

165 

166 
167 

167 

168 
168 
169 
169 

169 

170 

170 

171 

171 

172 

172 

173 

174 

175 

176 

177 


CONTENTS. 


V 


PAGE 


Description  of  species — Cont. 

Tellinidae — Cont. 

Macoma  (Cymatoica)  vendryesi .  .  178 

Semelidae .  178 

Semele  (Semele)  calliconcinnata. . .  178 

Abra  (Abra)  triangulata .  179 

Abra  (Abra)  deutera .  180 

Donacidae .  180 

Donax  (Donax)  species .  181 

Donax  (Paradonax)  lennoxi .  182 

Solenidae .  182 

Psamosolen  sancti-dominici .  182 

Mactridae . . .  183 

Spisula  (Mactromeris)  matleyi ....  184 

Mesodesmatidae .  184 

Ervilia  gabbi .  185 

Corbulidae . , .  185 

Corbula  (Corbula)  sericea .  186 

Corbula  (Corbula)  heterogena ....  187 
Corbula  (Bothrocorbula)  viminea.  189 

Basterotidae .  190 

Basterotia  (Basterotia)  bowdeni- 

ana .  191 

Gastrochaenidae .  191 

Gastrochaena  (Gastrochaena)  ro¬ 
tunda .  192 

Pholadidae .  193 

Jouannetia  sphaeroidalis .  193 

Martesia  bowdeniana .  194 

Xylophaga?  species .  195 

Teredidae .  195 

Teredo?  species .  195 


PAGE 


Description  of  species — Cont. 

Dentaliidae .  197 

Dentalium  (Dentalium)  cossman- 

nianum .  197 

Dentalium  (Dentalium)  glaucoter- 

rarum .  198 

Dentalium  (Dentalium?)  species  a.  198 
Dentalium  (Dentalium?)  species  b  199 
Dentalium  (Tesseracme)  dissimile 

dissimile . j. .  199 

Dentalium  (Tesseracme)  dissimile 

ponderosum .  200 

Dentalium  (Graptacme)  species  a.  201 
Dentalium  (Graptacme)  species  b  202 
Dentalium  (Laevidentalium)  hay- 

tense  .  202 

Dentalium  (Episiphon)  schumoi . .  203 
Dentalium  (Episiphon)  macilen- 

tum .  204 

Siphonodentaliidae .  204 

Cadulus  (Cadulus)  simrothi .  205 

Cadulus  (Gadilopsis)  dentalinus .  .  206 
Cadulus  (Gadilopsis)  hendersoni . .  207 
Cadulus  (Polyschides)  annulatus . .  207 
Cadulus  (Platyschides)  depres- 

sicolis .  209 

Cadulus  (Platyschides)  pilsbryi . . .  209 
Cadulus  (Platyschides)  species. ...  210 
Cadulus  (Platyschides)  annectens.  210 
Cadulus  (Platyschides)  arrosus.  . .  210 
Descriptions  of  plates .  211 


MIOCENE  MOLLUSKS  FROM  BOWDEN,  JAMAICA 

PELECYPODS  AND  SCAPHOPODS 


By  Wendell  P.  Woodring 


INTRODUCTION. 

This  report  is  one  of  a  series  dealing  with  the  geology  and  palaeon¬ 
tology  of  the  West  Indies  prepared  under  the  general  direction  of 
Dr.  T.  Wayland  Vaughan.  I  wish  to  express  my  deep  obligations 
to  Dr.  Vaughan  for  his  sustained  interest  in  the  work  and  for  the 
assistance  he  has  given  in  many  ways.  The  paper  contains  a  brief 
discussion  of  the  deposits  that  furnished  the  fossils  and  descriptions 
of  the  pelecypods  and  scaphopods.  It  is  expected  that  another  part 
may  be  issued  comprising  descriptions  of  the  gastropods  and  a  dis¬ 
cussion  of  the  fauna  and  its  significance. 

The  examination  of  the  fossils  described  in  this  report  was  begun 
at  Johns  Hopkins  University  in  1915.  A  fund  collected  by  Dr. 
William  Bullock  Clark,  who  was  then  head  of  the  Department  of 
Geology,  was  applied  to  a  continuation  of  the  work,  and  its  comple¬ 
tion  was  made  possible  by  a  grant  from  the  Carnegie  Institution  of 
Washington. 

It  was  soon  discovered  that  a  review  of  the  generic  nomenclature 
was  necessary  in  order  to  make  effective  comparisons  with  tropical 
Miocene  mollusks  in  other  parts  of  the  world  and  to  trace  the  former 
and  present  distribution  of  the  genera.  The  greatest  difficulty  arose 
from  the  determination  of  type  species.  In  fixing  the  types  of  genera 
I  have  attempted  to  follow  rigidly  the  International  Code  of  Zoo¬ 
logical  Nomenclature.  Article  30  (g)  of  the  Code  states  that — 

“If  an  author,  in  publishing  a  genus  with  more  than  one  valid  species, 
fails  to  designate  or  to  indicate  the  type,  any  subsequent  author  may  select 
the  type,  and  such  designation  is  not  subject  to  change.  (Type  by  subse¬ 
quent  designation.)  The  meaning  of  the  expression  ‘select  the  type’  is  to  be 
rigidly  construed.  Mention  of  a  species  as  an  illustration  or  example  of  a 
genus  does  not  constitute  a  selection  of  a  type.” 

It  was  obviously  impossible  to  search  all  the  literature  written  on 
mollusks  in  order  to  discover  the  earliest  designated  type  for  such 
genera.  A  paper  by  J.  E.  Gray,  entitled  “A  list  of  the  genera  of 
Recent  Mollusca,  their  synonyma  and  types/’  published  in  the  Pro¬ 
ceedings  of  the  Zoological  Society  of  London,  part  15,  pages  129  to 
219,  1847,  has  been  of  great  value.  In  this  paper  the  types  of  many 
old  genera  were  fixed,  although  many  writers  have  disregarded  it. 
In  order  to  prevent  any  misunderstanding,  I  have  followed  Iredale’s 
example  in  giving  the  reason  for  the  selection  of  the  type  of  each 
genus,  subgenus,  and  section.  The  authority  for  subsequent  desig¬ 
nation  is  given  for  subsequently  designated  types  except  for  some 

l 


2 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


genera  that  would  have  involved  too  extensive  a  search.  Some  of 
these  subsequently  designated  types  may  be  erroneous,  as  earlier 
designations  may  have  been  overlooked.  The  description  of  each 
group  is  based  on  an  examination  of  the  type  species  unless  otherwise 
designated. 

According  to  many  palaeontologists  and  malacologists,  the  generic 
names  in  the  Museum  Boltenianum  are  available  under  the  Code. 
This  matter  is  now  under  consideration  by  the  International  Commis¬ 
sion  of  Zoological  Nomenclature.  Unfortunately  these  Bolten  names 
displace  many  long-established  names. 

This  time-consuming  task  of  attempting  to  discover  what  generic 
names  should  be  used  has  no  direct  bearing  on  the  history  of  the 
earth  and  therefore  may  seem  like  wasted  time  for  a  palaeontologist. 
But  if  the  significance  of  the  genera  composing  a  fauna  is  considered, 
and  their  rise,  spread,  and  restriction  are  analyzed,  the  uniform  use 
of  generic  names  is  essential. 

The  extensive  collections  of  Tertiary  and  living  mollusks  in  the 
United  States  National  Museum  have  been  used  in  making  compari¬ 
sons  with  the  Bowden  mollusks.  Unless  otherwise  designated  the 
comparisons  are  based  on  an  examination  of  specimens. 

The  specimens  described  in  this  report  are  in  the  collections  of 
the  United  States  National  Museum  and  Johns  Hopkins  University. 
The  United  States  National  Museum  collections  include  the  Guppy 
collection,  which  contains  many  of  Guppy’s  types,  and  collections 
made  by  J.  B.  Henderson,  jr.,  and  C.  T.  Simpson  in  1894,  and  R.  T. 
Hill  in  1896.  The  Johns  Hopkins  University  collections  include 
material  sent  in  1899  by  J.  E.  Duerden  while  he  was  residing  in 
Kingston,  Jamaica,  and  collections  acquired  at  different  times  by 
T.  H.  Aldrich,  of  Birmingham,  Alabama.  I  have  also  had  access  to 
collections  at  the  Philadelphia  Academy  of  Natural  Sciences.  All 
these  collections  come  from  one  locality  at  Bowden  (see  p.  7) ;  there¬ 
fore  this  locality  is  the  type  locality  of  all  the  new  species  and  is  not 
repeated  in  the  descriptions  of  the  species. 

I  wish  to  record  my  grateful  thanks  for  assistance  and  criticism 
freely  given.  Professor  W.  B.  Clark  and  Professor  E.  W.  Berry 
generously  helped  in  many  ways  during  the  early  part  of  the  work. 
Dr.  T.  Wayland  Vaughan  gave  assistance  and  criticism  in  interpreting 
the  fauna  in  relation  to  the  geologic  history  of  the  West  Indies. 
Dr.  Paul  Bartsch  gave  access  to  the  facilities  of  the  Division  of 
Mollusks  of  the  United  States  National  Museum  and  constantly  gave 


INTRODUCTION. 


3 


advice.  Dr.  W.  H.  Dali,  whose  “Tertiary  Fauna  of  Florida”  is  the 
starting-point  of  any  work  dealing  with  American  Tertiary  mollusks, 
gave  access  to  the  collections  of  Tertiary  mollusks  in  the  United 
States  National  Museum  and  generously  gave  advice.  Dr.  Julia 
Gardner  kindly  helped  in  the  identification  of  fossils  and  in  the  inter¬ 
pretation  of  the  fauna.  Dr.  H.  A.  Pilsbry  gave  opportunities  to  study 
types  at  the  Philadelphia  Academy  of  Natural  Sciences.  Photographs 
of  the  type  of  Area  antiquata  Linne,  reproduced  as  figures  1  and  2  on 
plate  4,  were  furnished  by  B.  Daydon  Jackson,  general  secretary  of 
the  Linnean  Society  of  London.  L.  R.  Cox,  of  the  Department  of 
Geology,  British  Museum,  furnished  catalogue  numbers  of  the  types 
of  Miocene  mollusks  from  Jamaica  described  by  R.  J.  L.  Guppy,  and 
also  of  Miocene  mollusks  from  the  Dominican  Republic  described  by 
G.  B.  Sowerby  and  by  R.  J.  L.  Guppy. 


MARINE  TERTIARY  DEPOSITS  OF  JAMAICA. 

The  geological  map  published  in  1869  as  part  of  the  report  of  the 
official  survey1  still  is  the  most  detailed  geological  map  of  Jamaica. 
A  revised  but  more  generalized  map  was  issued  by  R.  T.  Hill  inl899.2 
Hill’s  map  corrected  some  mistakes  on  the  earlier  map  and  made 
other  changes,  some  of  which  have  not  been  verified  by  later  work.3 

In  1921,  Dr.  C.  A.  Matley,  who  had  recently  been  appointed  Gov¬ 
ernment  Geologist  of  Jamaica,  investigated  the  water  resources  of 
parts  of  the  island  where  the  stratigraphy  of  the  Tertiary  deposits 
was  an  essential  feature.  During  the  next  year  Dr.  Matley  brought 
to  Washington  extensive  collections  of  Tertiary  fossils,  principally 
from  the  parishes  of  Trelawny  and  St.  Ann.  The  brief  account  on 
the  following  pages  is  based  principally  on  these  collections,  which 
were  examined  by  Dr.  T.  W.  Vaughan  and  myself,  and  on  information 
furnished  by  Dr.  Matley. 

Dr.  C.  T.  Trechmann  and  others  have  recently  published  several 
valuable  papers  dealing  with  early  Tertiary  deposits  and  their  fossils. 

EOCENE. 

The  Carbonaceous  Shale  (Richmond  beds  of  Hill)  is  the  oldest 
Tertiary  deposit  in  Jamaica.  According  to  Trechmann,4  mollusks  in 
conglomerates  in  the  lower  part  of  the  deposit  indicate  a  lower  Eocene 
(Cuisian,  Sparnacian,  or  Thanetian)  age.  At  places  where  the  car¬ 
bonaceous  shale  is  missing,  it  may  be  represented  by  a  part  of  the 
overlying  Yellow  Limestone. 

The  middle  Eocene  (Lutetian)  Yellow  Limestone  (Cambridge  for¬ 
mation,  in  part,  of  Hill)  overlies  the  Carbonaceous  Shale,  but  at  places 
rests  directly  on  Upper  Cretaceous  limestone,  or  is  separated  from  it 
by  only  a  few  feet  of  shale.  Trechmann5 6  has  recently  described  the 
mollusks  of  the  Yellow  Limestone.  Its  tropical  fauna  differs  in  many 
features  from  the  middle  Eocene  faunas  of  the  Gulf  States  of  the 

1  James  G.  Sawkins,  and  others,  Reports  on  the  geology  of  Jamaica.  Part  2  of  the  West  Indian 
Survey,  Mem.  Geological  Survey  [Great  Britain],  339  pp.,  map,  8  unnumbered  plates  (sketches 
and  sections),  6  text-figs,  (one  unnumbered).  1869.  The  map  is  dated  1865. 

2  Robert  T.  Hill,  The  geology  and  physical  geography  of  Jamaica;  study  of  a  type  of  Antillean 
development.  Bull.  Mus.  Comp.  Zool.  Harvard  College,  vol.  34  (geological  series,  vol.  4),  256 
pp.,  41  plates,  40  text-figs.  1899. 

3  C.  A.  Matley,  Report  on  the  work  of  the  Government  Geologist  and  on  the  progress  of  the 
Geological  Surveys  in  Jamaica  for  economic  purposes.  Jamaica  Gazette  Supplement,  vol.  46, 
No.  9,  pp.  225-231.  July  4,  1923.  (See  p.  226.) 

*  C.  T.  Trechmann,  The  Carbonaceous  Shale  or  Richmond  Formation  of  Jamaica.  Geol. 

Mag.,  vol.  61,  pp.  2-19,  plates  1,  2.  1924. 

6  C.  T.  Trechmann,  The  Yellow  Limestone  of  Jamaica  and  its  Mollusca.  Geol.  Mag.,  vol.  60, 
pp.  337-367,  plates  14  to  18.  1923. 


4 


MARINE  TERTIARY  DEPOSITS. 


5 


United  States,  and  according  to  Trechmann  is  similar  to  the  Eocene 
fauna  of  Senegal.  The  Yellow  Limestone  also  carries  Foraminifera 
of  the  genera  Discocyclina,  Operculina,  and  Dictyoconus.  The  species 
of  Dictyoconus  are  similar  to  some  recently  described  from  deposits 
of  the  same  age  in  the  Republic  of  Haiti.1  The  echinoids  of  the 
Yellow  Limestone,  recently  described  by  Dr.  Hawkins,2  support  the 
evidence  furnished  by  the  mollusks  that  the  Yellow  Limestone  is  of 
middle  Eocene  age. 

Overlying  the  Yellow  Limestone  is  the  White  Limestone  (Mont¬ 
pelier  beds,  Moneague  and  Cobre  formations  of  Hill),  which  covers  a 
large  part  of  Jamaica.  Dr.  Matley’s  collections  show  that  the  White 
Limestone  includes  deposits  ranging  in  age  from  upper  Eocene  to 
upper  Oligocene  or  lower  Miocene.  The  lower  part,  of  upper  Eocene 
(Priabonian)  age,  carries  Foraminifera  of  the  genera  Alveolina  and 
Dictyoconus.  A  zone  carrying  both  Alveolina  and  Dictyoconus 
underlies  a  zone  containing  only  Dictyoconus.  This  part  of  the  White 
Limestone  seems  to  be  the  equivalent  of  similar  shoal-water  white 
limestones  in  the  nearby  islands  of  Haiti  and  Cuba  and  other  parts  of 
the  West  Indies. 

OLIGOCENE. 

r 

A  zone  of  the  White  Limestone  carrying  small  lenticular  species  of 
Lepidocyclina  may  be  of  lower  Oligocene  (Lattorfian)  age.  A  bed 
near  Claremont  in  the  parish  of  St.  Ann,  which  underlies  known 
middle  Oligocene  deposits,  carries  a  remarkable  gigantic  lucinoid 
mollusk,  described  by  Dali3  as  Lucina  megameris,  and  another  curious 
fossil  that  seems  to  be  a  gigantic  V erticordia.  Dr.  Matley  later  dis¬ 
covered  “Lucina”  megameris  at  a  locality  near  Kingston  in  beds 
containing  Dictyoconus.  The  “Lucina”  megameris  beds  may  be  upper 
Eocene  or  lower  Oligocene. 

A  considerable  part  of  the  White  Limestone  carries  large  species  of 
Lepidocyclina,  similar  to  species  characteristic  of  the  middle  Oligocene 
(Rupelian)  limestone  of  Antigua  and  other  parts  of  the  West  Indies 
and  of  Georgia,  Florida,  and  Alabama.  These  deposits  in  Jamaica 
also  contain  many  mollusks,  but  most  of  the  specimens  are  casts  or 
impressions.  Orthaulax  pugnax  (Heilprin),  which  has  been  found 
in  middle  and  upper  Oligocene  deposits  elsewhere,  is  represented  by 

1  W.  P.  Woodring,  in  W.  P.  Woodring,  J.  S.  Brown,  and  W.  S.  Burbank.  Geology  of  the 

Republic  of  Haiti,  Appendix  1,  pp.  608-609,  plate  9.  1924. 

2  H.  L.  Hawkins,  Notes  on  a  new  collection  of  fossil  Echinoidea  from  Jamaica.  Geol.  Mag., 

vol.  61,  pp.  312-324,  plate  18.  1924. 

*  W.  H.  Dali,  A  gigantic  fossil  Lucina.  Nautilus,  vol.  15,  pp.  40-42.  1901.  Synopsis  of  the 

Lucinacea  and  of  the  American  species.  Proc.  U.  S.  Nat.  Mus.,  vol.  23,  pp.  779-833,  plates  39  to 
42.  1901.  (See  pp.  829-830,  plate  42,  fig.  1.) 


6 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


a  cast  from  a  locality  near  Jackson  Town  in  the  parish  of  Trelawny. 
At  places  flint-bearing,  chalky,  and  globigerinal  beds,  called  Mont¬ 
pelier  beds  by  Hill,  lie  below  these  shallow-water  middle  Oligocene 
deposits.  According  to  Dr.  Matley’s  field  work,  this  type  of  beds 
does  not  lie  at  a  definite  stratigraphic  level,  but  seems  to  be  a  rela¬ 
tively  deep-water  facies  interfingering  with  shallow-water,  more  mas¬ 
sive  limestone  containing  mollusks  and  large  Foraminifera. 

The  upper  part  of  the  White  Limestone  contains  Foraminifera  of 
the  genus  Sorites.  It  seems  to  be  of  the  same  age  as  upper  Oligocene 
or  lower  Miocene  (Chattian  or  Aquitanian)  limestone  in  the  island  of 
Anguilla  and  elsewhere. 

MIOCENE. 

At  places  later  limestones  and  marls,  called  coastal  limestones 
by  Matley  and  a  variety  of  names  by  Hill,  overlie  the  White  Lime¬ 
stone  along  or  near  the  coast.  Their  age  ranges  from  Miocene  to 
Quaternary. 

A  limestone  at  May  Pen,  in  the  parish  of  Clarendon,  carries 
Orthaulax  aguadillensis  Maury,  an  upper  Oligocene  and  lower 
Miocene  fossil,  and  a  large  oyster  similar  to  Ostrea  cahobasensis 
Pilsbry  and  Brown,  a  lower  Miocene  species.  According  to  this 
evidence  the  limestone  at  May  Pen  is  lower  Miocene  (Burdigalian). 

The  deposits  called  Bowden  beds  and  Bowden  marl  by  earlier 
writers,  and  here  called  the  Bowden  formation,  are  middle  Miocene 
(Helvetian).  The  Bowden  mollusks  are  described  in  this  report. 

PLIOCENE. 

Some  of  the  coastal  limestones  may  be  Pliocene,  but  they  have  not 
been  adequately  studied.  Others  that  contain  living  species  of 
mollusks  and  corals  probably  are  Quaternary. 


BOWDEN  FORMATION. 

SOURCE  OF  DATA. 

I  regret  that  I  have  not  visited  Bowden.  The  following  account 
is  taken  from  the  descriptions  of  Sawkins  (1896,  p.  46), 1  Simpson 
(1894,  p.  433),  Hill  (1899,  pp.  82-84),  and  Henderson  and  Simpson 
(U.  S.  Geological  Survey  record  book  of  localities  of  Tertiary  inverte¬ 
brate  fossils,  station  2580),  supplemented  by  oral  information  from 
Henderson. 

NAME,  TYPE  LOCALITY,  AND  DISTRIBUTION. 

The  name  “Bowden  series”  was  first  used  by  Sawkins  in  1869 
(p.  44).  This  name  was  modified  to  “Bowden  beds”  and  “Bowden 
formation”  by  Hill  (1899,  pp.  9-13,  82-84,  145-152).  Later  writers 
have  followed  Dali  (1903,  p.  1580)  in  calling  these  deposits  the 
“Bowden  marl.”  As  they  consist  of  different  kinds  of  rock  forming 
a  mapable  unit,  they  are  here  called  the  Bowden  formation. 

The  type  locality  of  the  Bowden  formation  is  at  Bowden,  on  the 
east  side  of  Port  Morant,  in  the  parish  of  St.  Thomas,  lying  on  the 
south  coast  of  Jamaica  near  its  eastern  end.  The  beds  crop  out  on 
the  slope  of  the  hills  facing  the  bay.  At  the  time  when  Henderson 
and  Simpson  collected  there  (1894),  the  best  exposure  was  in  a  road- 
cut  about  100  yards  up  the  bay  from  a  pier  used  by  the  United  Fruit 
Company.  This  road-cut  was  at  the  foot  of  a  hill  on  which  stood 
a  house  occupied  by  Capt.  L.  D.  Baker,  an  official  of  the  company. 

Hill’s  map  shows  deposits  of  the  Bowden  formation  east  and  west 
of  the  type  locality  and  on  the  north  coast  east  of  Buff  Bay,  where 
a  Bowden  coral  was  collected  (Hill,  1899,  pp.  84,  149).  Detailed  field 
work  may  reveal  other  areas. 

LITHOLOGY,  STRUCTURE,  AND  THICKNESS. 

At  the  type  locality  a  bed  of  imperfectly  consolidated  gravel  con¬ 
sisting  of  small  pebbles  and  grains  of  igneous  rocks,  limestone,  and 
other  sorts  of  rock  in  a  marly  matrix  crops  out  in  the  road-cut  for  a 
distance  of  several  hundred  feet  along  the  bay.  This  bed,  which  is 
not  more  than  2  or  3  feet  thick,  contains  perfectly  preserved  fossils, 
and,  so  far  as  known,  has  furnished  all  the  fossils  collected  at  Bowden. 
Collectors  usually  shoveled  the  gravel  and  fossils  into  barrels,  a 
method  of  collecting  that  furnished  an  unusually  large  number  of 
small  specimens.  The  gravel  probably  lies  at  the  base  of  the  forma- 


1  See  reference  to  publications  in  footnote,  page  4,  and  in  list  on  pages  10-12. 

7 


8 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


tion,  but  the  underlying  deposits  are  not  exposed.  Overlying  the 
gravel  are  harder  beds  of  earthy  limestone  and  marl  containing  casts 
and  impressions  of  fossils.  Farther  up  the  hill,  which  rises  about  300 
feet  above  the  bay,  are  beds  of  marl,  clay,  and  sandstone.  Dr.  Matley 
discovered  poorly  preserved  plant  remains  in  these  beds.  The  beds 
dip  10°  or  less  south-southeastward.  The  total  thickness  of  the 
formation  as  exposed  at  the  type  locality  is  about  250  feet. 

STRATIGRAPHIC  RELATIONS. 

Although  the  contact  with  the  underlying  deposits  is  not  exposed 
at  the  type  locality,  the  Bowden  formation  clearly  is  a  fringing  coastal 
deposit  of  relatively  small  extent  overlying  the  White  Limestone. 
According  to  Hill  (1899,  p.  83),  the  position  of  the  Bowden  formation 
above  the  Yellow  Limestone  is  “f airly  well  revealed”  along  the  road 
from  Bath  to  Bowden,  but  no  description  is  given  of  the  contact  with 
the  White  Limestone.  No  information  is  available  concerning  the 
relations  to  overlying  beds. 

FOSSILS. 

Cushman1  has  described  30  species  and  subspecies  of  Foraminifera 
from  the  Bowden  formation.  Large  species  of  Haplostiche,  Cristel- 
laria,  and  Gypsina  are  most  abundant.  Countless  specimens  repre¬ 
senting  these  genera  drop  out  of  the  apertures  of  small  gastropods. 
Canu  and  Bassler2  have  described  17  species  and  subspecies  of  Bowden 
Bryozoa.  Vaughan  has  described  the  Bowden  corals,  but  his  report 
has  not  been  published.  In  1919  he  listed  17  species  and  described 
some  of  them.3 

Mollusks  are  so  abundant  that  their  description  has  lagged  behind 
the  other  fossils.  Fully  600  species  are  represented  in  the  collections 
examined  for  this  report.  Some  of  the  species  are  represented  by  hun¬ 
dreds  of  specimens.  This  report  describes  185  species  and  subspecies 
of  bivalves  and  20  species  and  subspecies  of  scaphopods. 

AGE. 

The  age  of  the  Bowden  formation,  the  relation  of  its  mollusks  to 
Miocene  mollusks  in  other  parts  of  the  world,  and  their  ecologic  sig¬ 
nificance  will  be  fully  discussed  later.  I  wish  to  record  here  the  bare 

1  J.  A.  Cushman,  Fossil  Foraminifera  from  the  West  Indies.  Carnegie  Inst.  Wash.  Pub.  No. 
291,  pp.  23-71,  15  plates,  8  text-figs.  1919. 

*  Ferdinand  Canu  and  R.  S.  Bassler,  Fossil  Bryozoa  from  the  West  Indies.  Carnegie  Inst. 
Wash.  Pub.  No.  291,  pp.  75-102,  7  plates.  1919. 

*  T.  W.  Vaughan,  Fossil  corals  from  Central  America,  Cuba,  and  Porto  Rico,  with  an  account 

of  the  American  Tertiary,  Pleistocene,  and  Recent  coral  reefs.  Bull.  U.  S.  Nat.  Mus.  103,  pp. 
189-524,  plates  68  to  152,  text-figs.  4  to  25.  1919.  (See  p.  212.) 


BOWDEN  FORMATION. 


9 


conclusion  that  the  Bowden  formation  is  of  middle  Miocene  (Helve¬ 
tian)  age.  It  approximately  is  the  equivalent  of  the  Gurabo  forma¬ 
tion  of  the  Dominican  Republic  and  the  Gatun  formation  of  Panama 
and  Costa  Rica.  Many  of  its  mollusks  are  similar  to  species  from  the 
Helvetian  deposits  of  the  Piedmont  basin  of  Italy. 

PREVIOUS  REPORTS. 

The  Bowden  formation  is  not  fully  described  in  the  report  of  the 
official  survey  of  Jamaica  published  in  1869.  Sawkins  mentions  these 
deposits  in  the  description  of  the  eastern  part  of  the  parish  of  St. 
Thomas  (pp.  44,  46).  In  this  report  the  Bowden  formation  is  con¬ 
fused  with  the  middle  Eocene  Yellow  Limestone.  Probably  all  the 
Miocene  mollusks  listed  on  page  152  and  on  pages  336-339  of  Appen¬ 
dix  V  are  Bowden  fossils,  except  “Cerithium  giganteum”  and  “Nerita 
schmideliana,”  which  clearly  represent  Yellow  Limestone  fossils. 
“Placuna  sinuosa”  may  refer  to  a  Bowden  Anomia- like  mollusk, 
perhaps  Placunanomia,  or  may  refer  to  a  Carolia  from  the  Yellow 
Limestone.  This  correlation  of  the  Bowden  formation  with  the 
Yellow  Limestone,  which  resulted  in  considering  the  Yellow  Lime¬ 
stone  Miocene,  is  evident  in  the  discussion  of  the  fossils  by  Robert 
Etheridge  in  Appendix  V  (pp.  307,  311-312,  319-329).  Hill  corrected 
this  mistake  (pp.  9-13),  and  more  fully  described  the  Bowden  forma¬ 
tion  (pp.  82-84)  and  its  fossils  (pp.  145-152). 

During  the  official  survey  Lucas  Barrett,  who  was  director  until 
his  untimely  death  in  the  field,  sent  to  the  British  Museum  a  collec¬ 
tion  of  Miocene  fossils.  J.  Carrick  Moore  discussed  the  significance 
of  these  fossils  in  a  paper  read  before  the  Geological  Society  of  London 
in  18631  and  compared  them  with  some  Miocene  fossils  discovered  by 
Colonel  Heneken  in  1849  in  the  Dominican  Republic  (“San  Domingo”). 
The  mollusks  in  this  collection  from  Jamaica  were  examined  by 
R.  J.  Lechmere  Guppy,  the  pioneer  investigator  of  West  Indian 
fossils,  while  he  was  in  London  in  1865,  and  a  paper  describing  them 
was  published  in  1866.  Although  the  collector  left  no  record  of  the 
locality,  there  is  no  reasonable  doubt  that  these  fossils  were  collected 
at  Bowden.  All  the  species  described  by  Guppy  are  Bowden  species 
and  such  perfectly  preserved  Miocene  shells  have  never  been  dis¬ 
covered  at  any  other  locality  in  Jamaica.  On  page  46  of  the  official 
survey  report,  Sawkins  states  that  at  Bowden  there  are  “beds  of  the 
most  perfect  Tertiary  shells  yet  found  on  the  island.” 

1  J.  Carrick  Moore,  On  some  Tertiary  shells  from  Jamaica.  Quart.  Jour.  Geol.  Soc.  London, 
vol.  19,  pp.  510-513.  1863. 


10 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


No  other  locality  than  “Miocene,  Jamaica/’  is  given  by  Guppy  in 
his  later  papers  listed  on  the  following  pages.  Probably  all  the  speci¬ 
mens  from  Jamaica  described  by  Guppy  in  these  later  papers  were 
sent  to  him  by  Mr.  Henry  Vendryes  of  Kingston,  who  informed  Hill 
(p.  147)  that  they  were  collected  at  Bowden. 

The  following  is  a  chronologic  list  of  reports  describing  Bowden 
mollusks : 

1866.  Guppy,  R.  J.  Lechmere.  On  the  Tertiary  Mollusca  of  Jamaica. 
Quart.  Jour.  Geol.  Soc.  London,  vol.  22,  pp.  281-295,  plates  16-18. 

Contains  descriptions  and  figures  of  27  new  species  and  brief  descriptions  of,  or 
references  to,  34  previously  described  species,  12  of  which  are  figured.  Speci¬ 
mens  of  23  of  the  new  species  in  the  Guppy  collection  at  the  United  States 
National  Museum  are  labeled  types,  although  the  actual  types  are  in  the 
British  Museum. 

1866.  Guppy,  R.  J.  Lechmere.  On  the  relations  of  the  Tertiary  forma¬ 

tions  of  the  West  Indies.  Quart.  Jour.  Geol.  Soc.  London,  vol.  22, 
pp.  570-590,  plate  26,  3  text  figs. 

Contains  list  (p.  575)  of  2  new  species  and  1  previously  described  species  from 
the  “Miocene  of  Jamaica.”  On  later  pages  (580-581)  the  new  species  are 
described  and  figured.  Jamaica  is  not  the  type  locality  of  these  new  species. 

1867.  Guppy,  R.  J.  Lechmere.  Notes  on  West  Indian  geology,  with 

remarks  on  the  existence  of  an  Atlantis  in  the  early  Tertiary  period; 
and  descriptions  of  some  new  fossils  from  the  Caribbean  Miocene. 
Geol.  Mag.,  vol.  4,  pp.  496-501,  6  text-figs. 

Contains  descriptions  and  figures  of  2  new  species  from  the  “Upper  Miocene  of 
Jamaica.”  The  types  are  in  the  Guppy  collection  at  the  United  States 
National  Museum. 

1867.  Guppy,  R.  J.  Lechmere.  On  the  Tertiary  fossils  of  the  West  Indies 
with  especial  reference  to  the  classification  of  the  Kainozoic  rocks 
of  Trinidad.  Proc.  Sci.  Assoc.  Trinidad,  pt.  3,  pp.  145-176.  Reprint 
in  Bull.  Amer.  Paleontology,  vol.  8,  pp.  172-203  (pp.  24-55  of 
Bull.  35).  1921. 

List  (pp.  155-164)  gives  67  species  of  mollusks  from  the  “upper  Miocene  of 
Jamaica.”  There  are  notes  on  one  of  these  species  (p.  171). 

1873.  Guppy,  R,  J.  Lechmere.  On  some  new  Tertiary  fossils  from  Jamaica. 
Proc.  Sci.  Assoc.  Trinidad,  vol.  2,  no.  2,  pt.  10,  pp.  72-88,  plates  1,  2. 
Reprint  in  Bull.  Amer.  Paleontology,  vol.  8,  pp.  204-220  (pp.  56-72 
of  Bull.  35).  1921. 

Contains  descriptions  of  20  new  species,  17  of  which  are  figured,  and  descriptions 
of,  or  references  to,  16  previously  described  species,  2  of  which  are  figured. 
The  types  of  the  new  species  are  in  the  Guppy  collection  at  the  United 
States  National  Museum.  According  to  Harris  (Bull.  Amer.  Paleontology, 
vol.  8,  footnotes  on  pp.  206-213,  215,  217,  218,  1921),  the  plate  references  in 
this  paper  refer  to  the  succeeding  paper,  but  an  original  copy  of  vol.  2,  no.  2, 
pt.  10  of  the  Proceedings  of  the  Scientific  Association  of  Trinidad,  December 
1873,  in  the  library  of  the  United  States  Geological  Survey  contains  the 
plates  referred  to  in  the  paper. 


BOWDEN  FORMATION. 


11 


1874.  Guppy,  R.  J.  Lechmere.  On  the  West  Indian  Tertiary  fossils.  Geol. 

Mag.,  decade  2,  vol.  1,  pp.  404-411;  433-446,  plates  16  to  18. 

Contains  redescriptions  of  18  of  the  new  species  described  in  the  precceding  paper, 
17  of  which  are  figured,  and  brief  descriptions  of,  or  references  to,  6  of  the 
other  species  considered  in  the  preceding  paper,  2  of  which  are  figured.  Also 
contains  figures  of  the  other  2  new  species  described  in  the  preceding  paper. 
They  are  again  described  in  the  succeeding  paper.  List  (pp.  437^443)  gives 
99  species  of  mollusks  from  the  “Miocene  of  Jamaica.” 

1875.  Guppy,  R.  J.  Lechmere.  Supplement  to  the  paper  on  West  Indian 

Tertiary  fossils.  Geol.  Mag.,  decade  2,  vol.  2,  pp.  41-42. 

Contains  redescriptions  of  the  2  new  species  described  in  1873  and  not  redescribcd 
in  1874. 

1882.  Guppy,  R.  J.  Lechmere.  On  the  Recent  and  Tertiary  species  of  Leda 
and  Nucula  found  in  the  West  Indies,  with  notices  of  Westindian 
shells.  Proc.  Sci.  Assoc.  Trinidad,  vol.  2,  no.  4,  part  12  (Dec. 
1881),  pp.  168-180,  plate  7.  Reprint  in  Bull.  Amer.  Paleontology, 
vol.  8,  pp.  237-249,  plate  9  (pp.  89-101,  plate  5  of  Bull.  35).  1921. 

Contains  descriptions  and  figures  of  3  new  species  and  descriptions  of  3  previously 
described  species,  2  of  which  are  figured,  from  the  “Miocene  of  Jamaica.” 
The  types  of  the  new  species  are  in  the  Guppy  collection  at  the  United  States 
National  Museum. 

1890-1903.  Dall,  William  Healy.  Contributions  to  the  Tertiary  fauna 
of  Florida,  with  especial  reference  to  the  Miocene  silex-beds  of 
Tampa  and  the  Pliocene  beds  of  the  Caloosahatchie  River.  Trans. 
Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3;  part  1,  pp.  1-200, 
plates  1  to  12, 1890;  part  2,  pp.  201-473,  map,  plates  13  to  22,  1892; 
part  3,  pp.  483-570,  1895;  part  4,  pp.  I-VIII,  571-947,  plates  23-35, 
1898;  part  5,  pp.  949-1218,  plates  36-47,  1900;  part  6,  pp.  I-XIV, 
1219-1654,  plates  48-60,  1903.  (The  following  was  added  to  the 
title  of  parts  4  to  6:  “Including  in  many  cases  a  complete  revision 
of  the  generic  groups  treated  of  and  their  American  Tertiary 
species.”) 

Parts  1  and  2  contain  brief  descriptions  of,  or  references  to,  11  previously  described 
species  of  gastropods  from  the  “Miocene  of  Bowden,  Jamaica.”  Parts  4  to 
6  contain  descriptions  of  58  new  species  of  pelecypods,  50  of  which  are 
figured;  descriptions  and  figures  of  3  other  new  species  reported  from 
Bowden,  although  the  type  locality  is  elsewhere;  brief  descriptions  of,  or 
references  to,  42  previously  described  species  and  4  indeterminable  species. 
The  locality  is  given  as  the  “Oligocene  of  Bowden,  Jamaica.”  Part  6  con¬ 
tains  (pp.  1580-1588)  a  discussion  of  the  fauna  and  a  fist  of  292  additional 
species  of  gastropods,  many  of  which  are  not  named,  10  species  of  scaphopods, 
and  12  additional  species  of  pelecypods,  making  a  total  of  432  species 
described  or  listed.  The  types  of  the  new  species  are  in  the  United  States 
National  Museum. 

1894.  Simpson,  Charles  Torrey.  Distribution  of  the  land  and  fresh¬ 
water  mollusks  of  the  West-Indian  region,  and  their  evidence  with 
regard  to  past  changes  of  land  and  sea.  Proc.  U.  S.  Nat.  Mus., 
vol.  17,  pp.  423-450,  plate  16. 


12 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Contains  descriptions  and  figures  of  3  new  species  of  land  snails  from  the 
“Miocene  beds  at  Bowden.”  The  types  are  in  the  United  States  National 
Museum.  These  shells  may  be  the  remains  of  living  shells  that  fell  into 
openings  in  the  ground  and  thus  were  collected  with  the  fossil  material. 

1896.  Guppy,  R.  J.  Lechmere,  and  William  Healy  Dall.  Descriptions 
of  Tertiary  fossils  from  the  Antillean  region.  Proc.  U.  S.  Nat. 
Mus.,  vol.  19,  pp.  303-331,  plates  27  to  30.  1896. 

Contains  descriptions  and  figures  of  33  new  species,  brief  descriptions  of,  or 
references  to,  20  previously  described  species  and  1  indeterminable  species 
from  the  “Oligocene  of  Jamaica.”  The  types  of  the  new  species  are  in  the 
United  States  National  Museum. 

1904.  Grabau,  W.  Amadeus.  Phylogeny  of  Fusus  and  its  allies.  Smith¬ 
sonian  Misc.  Coll.,  vol.  44,  No.  1417,  192  pp.,  18  plates,  22  text- figs. 

Contains  description  of  a  species  from  Bowden. 

1907.  Smith,  Burnett.  A  contribution  to  the  morphology  of  Pyrula. 

Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  59,  pp.  208-219,  plate  17, 
2  text-figs. 

Contains  description  and  figures  of  a  new  species  from  Bowden.  The  type  is  in 
the  Philadelphia  Academy  of  Natural  Sciences. 

1911.  Pilsbry,  Henry  A.  Scaphopods  of  the  Jamaican  Oligocene  and 
Costa  Rican  Pliocene.  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  63, 
pp.  165-169,  5  text-figs. 

Contains  descriptions  of  4  new  species,  3  of  which  are  figured,  2  indeterminable 
species,  and  references  to  3  previously  described  species  from  Bowden.  The 
types  of  the  new  species  are  in  the  Philadelphia  Academy  of  Natural 
Sciences. 

1913.  Cossmann,  M.  Etude  comparative  de  fossiles  mioceniques  recueillis 
a  la  Martinique  et  a  ITsthme  de  Panama.  Jour,  de  Conch.,  vol.  61, 
pp.  1-64,  plates  1  to  5. 

Contains  references  to  and  figures  of  3  species  of  gastropods  from  Bowden. 

1917.  Pilsbry,  H.  A.,  and  C.  W.  Johnson.  New  Mollusca  of  the  Santo 
Domingo  Oligocene.  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  69, 
pp.  150-202. 

Contains  description  (p.  194)  of  1  new  species  from  Bowden.  The  type  is  in  the 
Philadelphia  Academy  of  Natural  Sciences. 

1922.  Pilsbry,  Henry  A.  Revision  of  W.  M.  Gabb’s  Tertiary  Mollusca 
of  Santo  Domingo.  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  73, 
pp.  305-435,  plates  16  to  47,  48  text-figs. 

Contains  descriptions  (pp.  343,  360,  365)  and  figures  of  3  new  subspecies  from 
Bowden,  and  a  figure  of  the  new  species  described  in  the  preceding  paper. 
The  types  are  in  the  Philadelphia  Academy  of  Natural  Sciences. 


DESCRIPTION  OF  SPECIES. 

Class  PELECYPODA. 

Superfamily  NUCULACEA. 

Family  NUCULIDAE. 

Genus  NUCULA  Lamarck. 

Subgenus  NUCULA  s.  s. 

Section  NUCULA  s.  s. 

Lamarck,  1799,  Memoires  de  la  Societe  d’Histoire  Naturelle  de  Paris,  p.  87. 

Type  (by  monotypy ). — Area  nuculeus  Linne.  Recent,  seas  of 
Europe. 

The  following  is  a  description  of  the  section  Nucula  s.  s. : 

Shell  small,  trigonal,  inequilateral,  anterior  end  longer  than  posterior; 
interior  nacreous;  area  behind  umbo  slightly  or  strongly  depressed;  surface 
smooth  or  sculptured  with  fine  radials  or  concentric  rugae,  or  both;  chon- 
drophore  narrow,  oblique;  hinge  consisting  of  an  anterior  and  posterior 
series  of  chevron-shaped  teeth,  the  anterior  longer;  lower  margin  of  valve 
usually  finely  fluted. 

The  distribution  of  the  Tertiary  and  living  species  of  Nucula  is 
virtually  cosmopolitan.  They  are  more  abundant  and  reach  a  larger 
size  in  cool  water. 

Nucula  (Nucula)  morantensis,  new  species. 

(Plate  1,  Figure  1.) 

The  following  is  a  description  of  this  species: 

Shell  small,  subtrigonal,  moderately  inequilateral,  moderately  inflated; 
area  behind  umbo  definitely  depressed,  relatively  large,  cordate;  sculpture 
consisting  of  coarse  concentric  rugae  and  fine  radial  threads  between  the 
rugae;  sculpture  of  posterior  depressed  area  similar  to  that  of  remainder  of 
shell,  but  less  distinct;  hinge  heavy  for  size  of  shell,  anterior  series  slightly 
arcuate,  consisting  of  about  10  teeth,  posterior  series  shorter,  straight,  includ¬ 
ing  about  6  teeth;  inner  margin  of  valve  finely  fluted. 

Length  4.8  mm.;  height  4  mm.;  diameter  (left  valve)  0.9  mm. 

The  relatively  strong  sculpture  and  depressed  lunule-like  escutch¬ 
eon  are  characteristic  features  of  this  species.  It  is  larger  than 
N.  tenuisculpta  Gabb  from  the  Baitoa  and  Cercado  formations  of 
the  Dominican  Republic,  and  has  coarser  sculpture.  It  resembles 
N.  cahuitensis  Olsson,1  a  Miocene  species  from  Costa  Rica,  in  outline, 
but  has  coarser  sculpture,  larger  escutcheon,  and  no  lunule.  The 
Costa  Rican  species  closely  resembles  N.  vieta  Guppy,  described  from 
deposits  probably  of  Miocene  age  at  Matura,  Trinidad. 

The  holotype  of  N.  morantensis  has  both  valves  in  attached  posi¬ 
tion.  None  of  the  unattached  valves  is  perfect,  and  therefore  an 
interior  view  is  not  figured. 


1  Comparison  based  on  figures . 

13 


14 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Type  material. — Holotype  (both  valves  in  attached  position,  U.  S. 
Nat.  Mus.  No.  352727). 

Section  NUCOLOPSIS,  new  section. 

Type. — Nucula  ( Nuculopsis )  hilli  new  species. 

The  following  is  a  description  of  the  section  Nuculopsis: 

Shell  medium-sized,  subelliptical,  inequilateral;  sculpture  consisting  of 
strong  concentric  rugae;  chondrophore  long,  narrow,  oblique,  deeply  exca¬ 
vated;  anterior  series  of  teeth  more  than  twice  as  long  as  posterior  series; 
anterior  teeth  reduced  in  size  toward  chondrophore,  posterior  teeth  not 
reduced;  interior  of  valve  subnacreous;  lower  inner  margin  of  valve  smooth. 

The  outline  and  sculpture  of  Nuculopsis  and  Nucula  s.  s.  are  strik¬ 
ingly  different.  The  chondrophore  is  more  detached  from  the  anterior 
series  of  teeth  than  in  Nucula  s.  s.,  and  the  anterior  teeth  above  the 
chondrophore  are  much  smaller.  Externally  Nuculopsis  resembles 
some  of  the  subelliptical  species  of  the  genus  Tindaria,  but  the  liga¬ 
ment  of  Tindaria  is  wholly  external.  Apparently  no  similar  Tertiary 
or  living  species  has  been  described. 

Nucula  (Nuculopsis)  hilli,  new  species. 

(Plate  1,  Figures  2,  3.) 

The  following  is  a  description  of  this  species: 

Shell  thin,  polished;  sculpture  consisting  of  regular  concentric  rugae, 
crowded  and  less  prominent  on  dorsal  half  of  shell,  umbo  almost  smooth; 
chondrophore  relatively  large,  elongate,  subtriangular,  its  axis  oblique  and 
curved,  deeply  set,  placed  immediately  in  front  of  umbo;  teeth  short, 
anterior  series  longer,  moderately  curved,  including  15  or  16  teeth  pro¬ 
gressively  reduced  in  size  toward  the  chondrophore  and  continuing  almost 
to  tip  of  umbo,  the  last  few  teeth  lying  along  upper  anterior  margin  of 
chondrophore;  posterior  series  short,  straight  or  slightly  concave,  consisting 
of  5  or  6  teeth  of  virtually  the  same  size,  the  series  terminating  abruptly  at 
the  chondrophore. 

Length  8.9  mm.;  height  6.9  mm.;  diameter  (right  valve)  1.9  mm. 

The  living  West  Indian  species  N.  cymella  Dali  has  similar  con¬ 
centric  sculpture  and  smooth  inner  ventral  margin,  but  in  other 
features  is  a  Nucula  s.  s.  Externally  N.  hilli  resembles  subovate  or 
subelliptical  species  of  the  genus  Tindaria,  such  as  T.  smithii  Dali  and 
T.  cytherea  Dali,  living  West  Indian  species.  N.  hilli  is  not  so  strongly 
inflated  as  these  species  of  Tindaria  and  has  an  entirely  internal 
ligament. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352728). 


PELECYPODS. 


15 


Family  LEDIDAE. 

Genus  LEDA  Schumacher. 

Section  LEDA  s.  s. 

Schumacher,  1817,  Essai  d’un  Nouveau  Systeme  des  Habitations  des  Vers 
Testaces,  pp.  55,  172. 

Type  (by  monotypy). — Area  rostrata  Chemnitz  (=Mya  pernula 
Muller).  Recent,  seas  of  Europe. 

The  following  is  a  description  of  the  section  Leda  s.  s. : 

Shell  medium-sized,  elongate,  inequilateral,  posterior  end  rostrate  and 
slightly  gaping,  rostrum  bicarinate;  lunule  distinct;  sculpture  consisting  of 
concentric  rugae  on  dorsal  half  of  valve,  replaced  by  incrementals  on  ventral 
half;  hinge  consisting  of  an  anterior  and  posterior  series  of  chevron-shaped 
teeth,  posterior  series  almost  twice  as  long  as  anterior  series;  chondrophore 
small,  deep,  triangular;  pallial  sinus  shallow,  its  apex  narrowly  u-shaped. 

Most  of  the  living  species  of  the  section  Leda  s.  s.  live  in  the  cool 
seas.  There  are  no  species  in  the  Bowden  formation. 

Section  SACCELLA,  new  name. 

Ledina,  Sacco,  December  1898,  I  Molluschi  dei  Terreni  Terziarii  del  Piemonte 
e  della  Liguria,  pt.  26,  p.  53. 

Type  (by  original  designation). — Area  fragilis  Chemnitz  (=Leda 
commutata  Philippi).  Miocene  to  Recent,  Mediterranean  Sea. 

Not  Ledina  Dali,  April  1898  (Transactions  Wagner  Free  Institute 
of  Science  of  Philadelphia,  vol.  3,  pt.  4,  p.  580). 

Type  (by  original  designation). — Leda  eborea  Conrad  1860  (not 
L.  eborea  Conrad  1846)  —L.  smirna  Dali.  Eocene,  Gulf  States  of  the 
United  States). 

The  following  is  a  desciption  of  the  section  Saccella: 

Shell  small,  high,  slightly  inequilateral,  posterior  end  rostrate,  rostrum 
sharply  pointed  and  unicarmate;  a  shallow  groove  extends  from  the  umbo 
to  the  ventral  margin  at  both  ends  of  the  valve;  sculpture  consisting  of 
strong  concentric  rugae;  hinge  like  Leda  s.  s.,  but  the  anterior  and  posterior 
series  of  teeth  are  approximately  equal  in  length;  apex  of  pallial  sinus 
broadly  U-shaped. 

Saccella  resembles  the  section  Lembulus  Risso,1  but  has  a  narrower 
and  shallower  posterior  groove,  and  concentric  instead  of  diagonal 
sculpture.  There  are  no  American  late  Tertiary  or  living  species  of 
Lembulus.  The  geographic  distribution  and  difference  in  sculpture 
warrant  the  renaming  of  Sacco’s  section,  although  the  hinge  and 
pallial  sinus  of  Lembulus  and  Saccella  are  similar. 

Many  species  of  Saccella  have  been  described  from  Tertiary 
deposits.  Most  of  the  Tertiary  Ledas  from  tropical  America  are 
Saccellas.  Other  species  occur  in  the  subtropical  and  temperate 

1  Type  (by  subsequent  designation,  Gray,  1847). — Lembulus  rossianus  Risso  (=■  Area  pella 
Linn6).  Recent,  Mediterranean  Sea. 


16 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


faunas  of  Europe,  America,  and  elsewhere.  The  living  species  are 
widely  distributed. 

Key  to  the  Bowden  species  oj  Saccella. 

Sculpture  consisting  of  concentric  rugae. 

Length  of  adult  shell  exceeding  6  mm.,  sculpture  coarse . L.  ( S .)  peltella. 

Length  of  adult  shell  not  exceeding  6  mm.,  sculpture  fine . L.  ( S .)  subcerata. 

Sculpture  consisting  of  concentric  rugae  and  fine,  obscure  radial  threads 

in  the  interspaces . L.  ( S .)  indigena. 

Leda  (Saccella)  peltella  Dali. 

(Plate  1,  Figures  4,  5.) 

Leda  peltella  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3, 
part  4,  p.  579  (name  only),  plate  32,  fig.  5.  Not  Maury,  1917,  Bull.  Amer. 
Paleontology,  vol.  5,  p.  329,  plate  52,  fig.  9  {—L.  extricata  Pilsbry  and 
Johnson).  Not  Hubbard,  1921,  Scientific  Survey  of  Porto  Rico  and  the 
Virgin  Islands,  vol.  3,  pt.  2,  p.  104,  plate  17,  fig.  6,  New  York  Acad.  Sci. 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  plump;  lunule  narrow,  sculptured  with  coarse  threads 
not  continuous  with  the  concentric  rugae;  a  faint  groove  usually  lies  in 
front  of  the  rostral  ridge;  on  some  shells  an  obscure  groove  extends  from 
the  umbo  to  the  ventral  margin  at  the  anterior  end  of  the  shell;  sculpture 
consisting  of  regular,  closely  set  concentric  rugae,  extending  across  the 
rostral  ridge  and  escutcheon,  terminating  at  the  edge  of  the  narrow  lunule; 
about  20  teeth  lie  in  front  of,  and  15  behind  the  small  chondrophore. 

Length  8.8  mm.;  height  5.8  mm.;  diameter  (right  valve)  2.4  mm. 

Type  locality. — Bowden,  Jamaica. 

The  absence  of  concentric  rugae  on  the  lunule  is  a  characteristic 
feature  of  this  species,  which  is  the  most  abundant  Leda.  Most  of 
the  shells  are  high,  but  some  are  relatively  long.  The  posterior 
groove  is  not  so  strong  as  in  the  figure  given  by  Dali.  The  anterior 
groove  usually  is  indicated  only  by  a  slight  displacement  of  the 
rugae. 

Dali  considered  this  species  the  same  as  Leda  acuta  Gabb,  a  Mio¬ 
cene  species  from  the  Dominican  Republic,  and  substituted  the  name 
peltella  for  the  preoccupied  name  acuta,  but  figured  a  Bowden  shell 
and  designated  a  Bowden  shell  as  type  material.  Pilsbry  and  Johnson 
have  described  the  Dominican  species  as  L.  extricata.  L.  peltella 
closely  resembles  L.  extricata,  but  is  less  elongate  and  more  inflated, 
and  has  a  different  lunule  and  escutcheon. 

The  Leda  from  the  Quebradillas  limestone  of  Porto  Rico  described 
by  Hubbard  as  L.  peltella  is  larger  and  more  elongate  than  Bowden 
specimens,  and  its  posterior  end  is  less  distinctly  grooved.1 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135753). 


1  Comparison  based  on  figures. 


PELECYPODS. 


17 


Leda  (Saccella)  subcerata,  new  species. 

(Plate  1,  Figures  6,  7.) 

The  following  is  a  description  of  this  species: 

Shell  small,  polished,  elongate,  virtually  equilateral;  rostrum  blunt, 
slightly  recurved;  umbos  full,  strongly  incurved;  escutcheon  poorly  defined, 
bounded  by  a  low  rounded  ridge;  area  in  front  of  umbo  slightly  depressed, 
but  not  forming  a  lunule;  sculpture  consisting  of  fine  rugae,  more  sharply 
sculptured  and  crowded  on  ventral  half  of  shell,  continuous  across  depressed 
areas,  both  before  and  behind  umbo;  chondrophore  relatively  narrow  and 
long;  about  16  teeth  in  anterior  series  and  13  in  posterior;  chondrophore 
very  small,  deeply  inset;  muscle  scars  relatively  large. 

Length  5.8  mm.;  height  3.4  mm.;  diameter  (right  valve)  1.3  mm. 

The  elongate  equilateral  outline,  polished  surface,  and  ventral 
crowding  of  the  rugae  are  characteristic  features  of  this  species.  It 
closely  resembles  the  living  West  Indian  L.  cerata  Dali,  but  is  smaller, 
and  has  fuller  umbos  and  more  strongly  upturned  rostrum.  It  also 
resembles  L.  vitrea  d’Orbigny,  but  d’Orbigny’s  species  has  not  been 
certainly  identified. 

Three  of  the  4  cotypes  of  L.  perlepida  Guppy  (U.  S.  Nat.  Mus.  No. 
115557),  from  beds  probably  of  Miocene  age  at  Matura,  Trinidad, 
are  young  shells  that  are  virtually  indistinguishable  from  young, 
unusually  high  shells  of  L.  subcerata.  The  other  shell,  which  was 
figured,  has  concentric  waves  in  addition  to  rugae. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  352729) 

Leda  (Saccella)  indigena  Dali. 

(Plate  1,  Figures  8  to  10.) 

Leda  bisulcata  Guppy,  1867,  Geol.  Mag.  decade  1,  vol.  4,  pp.  500-501,  fig.  2. 
Guppy,  1874,  Geol.  Mag.  decade  2,  vol.  1,  p.  442  (list).  Guppy,  1882, 
Proc.  Sci.  Assoc.  Trinidad,  part  12,  p.  173,  plate  7,  fig.  7.  Not  L.  bisulcata 
Meek  and  Hayden,  1861. 

Leda  indigena  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3, 
part  4,  p.  579  (name  only). 

The  following  is  the  original  description  of  Leda  bisulcata  Guppy: 

Shell  ovately  trigonal,  with  numerous  concentric  ribs  narrower  than 
their  interstices;  with  a  somewhat  sinuous  elevated  ridge  running  from  the 
umbo  to  the  pointed  rostrum  behind;  rounded  anteriorly  with  a  round 
groove  running  from  the  umbo  to  the  ventral  margin  near  the  anterior 
angle.  Umbones  close;  posterior  dorsal  area  flat,  sloping,  striate  continu¬ 
ously  with  the  ribs  of  the  disc;  no  very  distinct  anterior  area.  Teeth  very 
prominent. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  moderately  inequilateral;  posterior  end  sharply  rostrate, 
rostrum  slightly  recurved;  lunule  not  differentiated,  represented  by  a  slightly 
depressed  narrow  zone;  escutcheon  sharply  differentiated,  broad,  extending 
to  tip  of  rostrum,  bounded  by  a  strong  ridge;  immediately  in  front  of  the 


18 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


rostral  ridge  a  shallow  groove  extends  from  the  umbo  toward  the  ventral 
margin;  near  the  anterior  end  a  shallow  groove  extends  from  the  umbo  to 
the  ventral  margin;  sculpture  concentric  and  radial,  concentric  sculpture 
consisting  of  closely-set  rugae,  equally  strong  over  entire  valve  and  per¬ 
sisting  across  the  rostral  ridge  and  escutcheon;  radial  sculpture  consisting 
of  fine  threads  confined  to  the  interspaces,  strongest  near  the  grooves;  about 
15  teeth  lie  behind,  and  16  teeth  in  front  of  the  deeply  set  small  triangular 
chondrophore. 

Length  6.5  mm.;  height  3.8  mm.;  diameter  (left  valve)  1.5  mm. 

This  abundant  species  is  recognized  by  the  pointed  slightly 
recurved  rostrum ;  sharp  posterior  ridge ;  broad,  long  escutcheon  that 
is  conspicuously  sculptured  by  the  concentric  rugae;  and  fine  radial 
sculpture. 

L.  indig ena  resembles  L.  acuta  (Conrad)  which  ranges  from  the 
upper  Miocene  to  the  Recent  and  also  has  a  wide  geographical  range. 
The  Bowden  species  is  smaller,  less  elongate,  and  has  a  recurved 
rostrum  and  more  constantly  fine  concentric  sculpture  than  L.  acuta. 
L.  dodona  Dali,  from  the  Oak  Grove  sand  of  Florida,  belongs  to  the 
same  group.  It  has  very  coarse  concentric  rugae  and  an  almost 
smooth  escutcheon.  A  species  from  the  Chipola  formation  of  Florida, 
L.  trochilia  Dali,  has  wide  spaces  between  the  discontinuous  and 
irregular  rugae,  and  no  rugae  on  the  rostral  ridge.  None  of  these 
species  has  the  radial  threads  of  L.  indigena.  L.  davilae  Olsson,1  a 
Miocene  species  from  Costa  Rica  and  Panama,  has  similar  radial 
threads,  but  is  higher  than  L.  indigena. 

Type  material. — 3  cotypes  (“types”  of  L.  bisulcata  Guppy,  U.  S. 
Nat.  Mus.  No.  115553). 

Section  JUPITERIA  Bellardi. 

Bellardi,  1875,  Monografia  della  Nuculidi  Trovate  Finora  nei  Terreni  Terziari- 
del  Piemonte  e  della  Liguria,  p.  20. 

Type  ( by  subsequent  designation,  Dali,  1898). — Nucula  concava 
Bronn.  Pliocene,  Italy. 

The  following  is  a  description  of  the  section  Jupiteria : 

Shell  small,  corbuloid,  strongly  inflated,  subequilateral,  bluntly  rostrate, 
rostrum  barely  ridged;  area  behind  umbo  flattened  but  not  depressed; 
sculpture  consisting  of  obscure  concentric  rugae;  hinge  consisting  of  an 
anterior  and  posterior  series  of  chevron-shaped  teeth,  approximately  equal 
in  length;  chondrophore  small,  triangular,  deep;  pallia!  sinus  shallow,  its 
apex  broadly  U-shaped. 

The  corbuloid  outline,  blunt  and  barely  ridged  rostrum,  and  shallow 
sinus  separate  this  section  from  the  other  sections  of  Leda.  Exter¬ 
nally,  Jupiteria  closely  resembles  rostrate  species  of  Tindaria. 

The  Bowden  species  described  on  the  following  pages  are  the  only 
known  American  Tertiary  Ledas  similar  to  Leda  concava  (Bronn). 


1  Comparison  based  on  figures. 


PELECYPODS. 


19 


Several  Miocene  species  have  been  described  from  the  Mediterranean 
region,  and  2  species  are  recorded  from  lower  Oligocene  deposits  in 
Germany.  There  are  no  living  European  species  of  Jupiteria,  but  it 
is  represented  in  the  Gulf  of  Mexico  by  Leda  solidijacta  Dali.  This 
section  of  Leda  is  one  of  many  groups  that  lived  in  West  Indian  and 
Mediterranean  waters  during  Miocene  time  but  now  are  restricted  to 
West  Indian  or  adjacent  waters. 

Key  to  the  Bowden  species  of  Jupiteria. 

Length  of  adult  shell  exceeding  5  mm . L.  (J .)  bowdenesis 

Shell  relatively  high .  L.  ( J .)  bowdenensis  bowdenensis 

Shell  elongate .  L.  (/.)  bowdenensis  subtumida 

Length  of  adult  shell  not  exceeding  5  mm .  L.  (J.)  duerdeni 

Leda  (Jupiteria)  bowdenensis  bowdenensis,  new  species  and  subspecies. 

(Plate  1,  Figures  11,  12.) 

The  following  is  a  description  of  this  subspecies: 

Shell  small,  elongate  subtrigonal;  umbos  high,  very  full,  strongly  in¬ 
curved;  area  behind  umbo  flattened;  posterior  ridge  low,  broad;  sculpture 
consisting  of  irregularly  spaced  fine  concentric  striae,  absent  on  umbos  and 
in  area  within  posterior  ridge,  coinciding  with  irregularly  spaced  growth 
lines  on  ventral  half  of  shell;  chondrophore  triangular,  relatively  broad; 
about  19  teeth  in  the  slightly  convex  anterior  series  and  about  13  teeth  in 
the  concave  posterior  series,  median  teeth  small  and  obscure;  muscle  scars 
faint,  relatively  large. 

Length  6.2  mm.;  height  4.5  mm.;  diameter  (right  valve)  1.9  mm. 

This  subspecies  is  similar  to  L.  concava  (Bronn),  the  type  of  the 
section,  from  the  Plaisancian  of  the  Piedmont  basin,  northern  Italy. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 

352731). 

Leda  (Jupiteria)  bowdenensis  subtumida,  new  subspecies. 

(Plate  1,  Figures  13,  14.) 

The  following  is  a  description  of  this  subspecies: 

Shell  resembling  L.  bowdenensis  bowdenensis,  but  more  elongate  and 
slightly  less  inflated;  umbos  lower  and  less  full;  ventral  margin  less  curved; 
sculpture  coarser  and  more  irregular;  chondrophore  broader;  hinge  having 
about  13  teeth  in  each  series ;  anterior  series  more  convex  and  posterior  less 
concave  than  in  L.  ( J .)  bowdenensis  bowdenensis. 

Length  6.5  mm.;  height  4  mm.;  diameter  (right  valve)  1.7  mm. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352732). 

Leda  (Jupiteria)  duerdeni,  new  species. 

(Plate  1,  Figures  15,  16.) 

The  following  is  a  description  of  this  species: 

Shell  small,  polished,  rounded  triangular,  strongly  inflated;  umbo  high, 
full;  area  behind  umbo  distinctly  flattened;  rostral  ridge  low,  broad; 
sculpture  consisting  of  fine  evenly  spaced  concentric  rugae,  absent  on  top 


20 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


of  umbo  and  in  area  bounded  by  rostral  ridge,  sculpture  on  some  shells 
absent  on  posterior  half  or  entire  surface  of  shell;  chondrophore  large, 
triangular,  lying  below  and  just  in  front  of  tip  of  umbo;  anterior  series  of 
teeth  including  about  13,  posterior  series  16. 

Length  4.9  mm.;  height  3.4  mm.;  diameter  (left  valve)  0.9  mm. 

L.  duerdeni  is  smaller  and  higher  than  L.  bowdenensis  and  has  a 
shorter  and  more  acute  rostrum,  stronger  ridge,  more  regular  and 
more  delicate  sculpture,  larger  chondrophore,  and  heavier  hinge. 
Externally  it  resembles  the  rostrate  Tindarias,  for  which  Verrill  and 
Bush1  proposed  the  name  Tindariopsis. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352733). 

Section  PSEUDOPORTLANDIA,  new  section. 

Type. — Leda  clara  Guppy.  Miocene,  Jamaica. 

The  following  is  a  description  of  the  section  Pseudoportlandia: 

Shell  heavy,  medium  sized,  moderately  inflated,  upper  posterior  margin 
bluntly  rostrate,  lower  posterior  margin  truncated;  sculpture  consisting  of 
obscure  striae;  hinge  consisting  of  an  anterior  and  posterior  series  of  heavy 
chevron-shaped  teeth,  anterior  series  slightly  longer;  chondrophore  wide, 
triangular,  moderately  deep ;  pallial  sinus  apparently  shallow. 

In  outline  Leda  clara  is  remarkably  similar  on  a  small  scale  to 
Yoldia  glacialis  (Gray),  the  type  of  the  section  Portlandia  Morch, 
which  is  restricted  to  boreal  waters.  The  Bowden  species  has  a  rela¬ 
tively  heavier  hinge,  much  shallower  chondrophore,  and  apparently 
a  shallower  pallial  sinus.  The  outline,  heavy  hinge,  and  wide  chon¬ 
drophore  distinguish  Pseudoportlandia  from  other  sections  of  Leda. 
In  many  features  Pseudoportlandia  is  intermediate  between  Leda 
and  Yoldia,  but  the  rostrum  and  apparent  shallow  sinus  indicate  that 
it  more  closely  resembles  Leda. 

The  following  Bowden  species  and  a  similar  undescribed  species 
from  the  Gurabo  formation  of  the  Dominican  Republic  are  the  only 
known  species  of  Pseudoportlandia. 

Leda  (Pseudoportlandia)  clara  Guppy. 

(Plate  1,  Figures  17  to  19.) 

Leda  clara  Guppy,  1873,  Proc.  Sci.  Assoc.  Trinidad,  vol.  2,  no.  2,  p.  87,  plate  2, 
figs.  1,  la.  Guppy,  1874,  Geol.  Mag.  decade  2,  vol.  1,  p.  442  (list),  plate 
17,  figs.  1,  la.  Guppy,  1875,  Geol.  Mag.  decade  2,  vol.  2,  p.  42.  Guppy, 
1882,  Proc.  Sci.  Assoc.  Trinidad,  part  12,  p.  172,  plate  7,  fig.  4. 

The  following  is  the  description  of  this  species  published  by  Guppy 
in  1875: 

Subelliptical,  lanceolate,  nearly  equilateral,  somewhat  but  not  extremely 
rostrated.  Disk  smooth,  shining;  valve  with  a  few  fine,  close,  regular  con¬ 
centric  riblets  perceptible  near  the  anterior  angle,  where  an  indistinct  sulcus 
runs  upwards  towards  the  umbo.  No  distinct  escutcheon.  Lunule  narrow, 


1  A.  H.  Verrill,  and  K.  Bush,  Amer.  Jour.  Sci.,  ser.  4,  vol.  3,  p.  59.  1807 


PELECYPODS. 


21 


indistinctly  defined.  Umbos  prominent.  Ventral  margin  slightly  angulated 
at  about  a  third  of  its  length  from  the  posterior  point,  where  an  obscure 
carina  runs  to  the  margin  from  the  umbo. 

Length  12  mm. ;  height  6  mm. ;  thickness  about  4  mm. 

Type  locality. — Jamaica. 

The  following  supplements  Guppy’s  description  of  this  species: 

Shell  medium-sized,  heavy,  subequilateral ;  anterior  dorsal  margin  con¬ 
vex,  posterior  dorsal  margin  excavated;  umbo  low,  approximately  central; 
lunule  not  differentiated,  represented  by  a  very  narrow,  slightly  flattened 
area;  area  behind  umbo  wider,  flattened;  rostral  ridge  lying  near  dorsal 
margin,  low,  broad;  ventral  third  of  shell  bearing  a  broad,  shallow  groove 
in  front  of  rostrum,  the  groove  very  slightly  emarginating  the  truncated 
posterior  margin;  sculpture  consisting  of  fine  striae,  accentuated  by  irregu¬ 
larly  spaced  incrementals  on  ventral  half  of  shell;  chondrophore  large; 
anterior  series  of  teeth  including  about  19  teeth,  posterior  series  15. 

Length  13.5  mm.;  height  7.5  mm.;  diameter  (right  valve)  2.3  mm. 

This  species  is  the  largest  Bowden  Leda.  Young  shells  are  only 
slightly  truncated  below  the  blunt  rostrum,  but  on  full-grown  shells 
the  truncation  is  prominent.  The  pallial  line  is  obscure  on  all  valves, 
but  on  some  there  appears  to  be  a  shallow  sinus. 

A  fragment  of  a  very  similar  species  was  collected  from  the  Gurabo 
formation  (station  8528)  in  the  Dominican  Republic.  The  Dominican 
shell  is  slightly  larger  and  has  stronger  sculpture. 

Type  material. — 4  cotypes  (U.  S.  Nat.  Mus.  No.  115558). 

Genus  YOLDIA  Moller. 

Section  YOLDIA  s.  s. 

Moller,  1842,  Index  Molluscorum  Groenlandiae,  p.  18. 

Type  (by  subsequent  designation). — Nucula  arctica  Moller  not 
Gray  (=Nucula  myalis  Couthouy).  Recent,  northern  seas  of  Europe. 

The  following  is  a  description  of  the  section  Yoldia  s.  s.: 

Shell  moderately  large,  subovate,  slightly  rostrate;  sculpture  consisting 
of  growth-lines  or  concentric  striae;  hinge  consisting  of  2  subequal  series 
of  small  chevron-shaped  teeth;  chondrophore  large,  wide,  triangular,  extend¬ 
ing  far  below  the  teeth;  pallial  sinus  deep,  wide,  the  apex  broadly  u-shaped. 

There  are  no  Tertiary  or  living  species  of  Yoldia  s.  s.  in  tropical 
America. 


Section  ORTHOYOLDIA  Verrill  and  Bush. 

Verrill  and  Bush,  1897,  American  Journal  of  Science,  ser.  4,  vol.  3,  p.  55. 

Type  (by  original  designation). — Yoldia  scapania  Dali.  Recent, 
coast  of  Brazil. 

The  following  is  a  description  of  the  section  Orthoyoldia: 

Shell  medium-sized,  solenoid;  sculpture  consisting  of  obscure  striae;  hinge 
consisting  of  2  series  of  small  chevron-shaped  teeth,  posterior  series  longer 


22 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


than  anterior;  chondrophore  relatively  small,  wide,  triangular;  pallial  sinus 
deep,  very  wide,  the  apex  broadly  u-shaped. 

In  outline  Orthoyoldia  and  Yoldia  s.  s.  are  strikingly  different;  the 
disparity  in  length  of  the  two  series  of  teeth  is  greater  in  Orthoyoldia, 
and  its  chondrophore  is  not  so  high.  The  Bowden  species,  Yoldia 
ovalis  Gabb,  has  more  prominent  umbos  and  more  distinct  sculpture 
than  the  type  of  the  section,  but  the  hinges  of  the  two  species  are 
similar. 

Orthoyoldia  is  a  tropical  and  subtropical  American  group.  Yoldia 
pasammotaea  Dali,  a  Claiborne  (middle  Eocene)  species,  may  be  an 
Orthoyoldia,  but  its  hinge  is  not  known.  Yoldia  serica  Conrad,  an 
Oligocene  species,  seems  to  be  an  Orthoyoldia. 

Yoldia  (Orthoyoldia)  ovalis  Gabb. 

(Plate  1,  Figures  20,  21.) 

Yoldia  ovalis  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol.  15,  pp.  255-256. 

Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.,  Philadelphia,  vol.  73,  p.  402,  text  fig.  34. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  compressed,  subelliptical;  beaks  slightly  in  front  of  middle; 
hinge  line  sloping  gently,  base  and  ends  rounded;  surface  smooth  or  bearing 
a  few  faint  impressed  concentric  lines  on  anterior  part  near  base.  Length 
0.35  inch,  width  0.15  inch. 

Type  locality. — Dominican  Republic. 

The  following  is  a  description  of  Bowden  specimens  of  this  species: 

Shell  medium-sized,  thin,  polished,  subelliptical,  posterior  end  compressed, 
umbos  low;  behind  the  umbo  lies  a  narrow,  slightly  depressed  area  sculp¬ 
tured  with  relatively  coarse,  oblique  threads  and  having  a  heavier  thread 
parallel  to  and  scarcely  separated  from  inner  edge  of  the  area;  in  front  of 
the  umbo  lies  a  similar  shorter  area;  sculpture  consisting  of  fine,  incon¬ 
spicuous  striae,  absent  in  umbonal  and  posterior  regions,  and  on  some  shells 
entirely  absent;  chondrophore  small,  wide;  the  two  series  of  teeth  diverging 
at  a  very  obtuse  angle;  about  18  teeth  in  anterior  and  20  in  posterior  series; 
anterior  teeth  larger,  in  both  series  the  size  reduced  gradually  toward  point 
of  divergence;  muscle  scars  obscure;  pallial  sinus  deep,  moderately  wide. 

Length  8.8  mm.;  height  5  mm.;  diameter  (left  valve)  1.8  mm. 

The  depressed  areas  before  and  behind  the  umbo  are  very  narrow. 
They  are  more  deeply  depressed  than  in  specimens  from  the  Gurabo 
formation  of  the  Dominican  Republic.  The  Dominican  specimens 
have  no  sculpture  except  a  few  low  concentric  waves  in  the  middle 
lower  part  of  the  shell.  Most  Bowden  specimens  have  fine  striae. 

Olsson1  has  described  a  similar  species,  Yoldia  bocasensis,  from 
Miocene  beds  on  Bocas  Island,  Panama.  It  apparently  is  a  little  more 
inequilateral.  Y.  ovalis  is  similar  to  F.  solenoides  Dali,  a  living 
species  from  the  Gulf  of  Mexico,  but  is  less  elongate,  and  has  a 
slightly  more  prominent  and  acute  umbo.  The  hinges  of  the  two 


1  Comparison  based  on  figures. 


PELECYPODS. 


23 


species  are  very  similar.  In  outline  Y.  ovalis  closely  resembles 
elongate  species  of  the  genus  Malletia. 

Other  localities . — Gurabo  formation  (middle  Miocene),  Dominican 
Republic. 

Type  material. — Holotype  (left  valve,  Acad.  Nat.  Sci.  Philadel¬ 
phia  No.  3319). 

Family  MALLETIIDAE. 

Genus  TINDARIA  Bellardi. 

Section  TINDARIA  s.  s. 

Bellardi,  1875,  Monografia  della  Nuculidi  Trovate  Finora  nei  Terreni  Terziari 
del  Piemonte  e  della  Liguria,  p.  28. 

Type  {by  monotypy). — Tindaria  arata  Bellardi.  Miocene  and 
Pliocene,  Italy. 

The  following  is  a  description  of  the  section  Tindaria  s.  s.: 

Shell  small,  veneroid,  strongly  inflated;  umbos  full,  prosogyrate;  sculp¬ 
ture  consisting  of  more  or  less  distinct  concentric  rugae;  ligament  external, 
opisthodetic ;  hinge  uninterrupted  below  umbo,  posterior  series  strongly 
curved,  anterior  series  shorter,  straighter,  and  consisting  of  heavier  teeth; 
pallial  sinus  moderately  deep,  the  apex  v-shaped. 

The  outline,  prosogyrate  umbos,  and  hinge  distinguish  Tindaria 
from  other  genera  in  the  family  Malletiidae,  which  is  characterized 
by  an  external  ligament. 

Tindaria  is  one  of  many  genera  that  lived  in  the  West  Indian  and 
Mediterranean  regions  during  Miocene  and  Pliocene  time,  but  have 
survived  in  West  Indian  and  adjacent  waters  and  not  in  European 
seas.  The  following  species  is  the  only  known  American  Tertiary 
species.  Miocene  deposits  have  furnished  the  oldest  species  on  both 
sides  of  the  Atlantic. 

Tindaria  (Tindaria)  species. 

(Plate  1,  Figures  22,  23.) 

The  following  is  a  description  of  this  species: 

Shell  small,  polished,  subovate,  moderately  inequilateral;  sculpture  con¬ 
sisting  of  regularly  spaced,  relatively  coarse  concentric  rugae,  absent  on 
umbo  and  near  dorsal  margins;  ligament  external,  opisthodetic,  the  area 
very  narrow  and  shallow,  obscurely  truncating  upper  part  of  inner  posterior 
teeth;  teeth  in  two  series,  barely  interrupted  under  the  umbo;  the  convex 
posterior  series  of  15  teeth  reduced  in  size  toward  umbo  and  the  dorsal 
parts  of  the  7  inner  teeth  obscured  by  immersion  of  ligament;  anterior 
series  slightly  concave,  including  7  teeth,  the  outer  5  heavy  and  the  inner 
2  abruptly  reduced  in  size;  interior  of  shell  polished;  anterior  muscle  scar 
relatively  large,  placed  under  end  of  hinge;  posterior  scar  and  pallial  line 
obscure. 

Length  3.5  mm.;  height  2.5  mm.;  diameter  (left  valve)  1.2  mm. 

The  left  valve  on  which  this  description  is  based  was  broken  and  a 
piece  lost  after  the  description  was  written.  It  is  smaller  and  less 


24 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


elongate  than  the  living  West  Indian  species  T.  cytherea  Dali  and 
differs  also  in  hinge  characters.  The  Bowden  species  more  closely 
resembles  T.  panamensis  Dali  from  the  Gulf  of  Panama,  but  is 
shorter  and  its  posterior  end  is  more  inflated. 

Superfamily  ARCAEA. 

Family  ARCIDAE. 

Genus  GLYCYMERIS  da  Costa. 

Subgenus  GLYCYMERIS  s.  s. 

da  Costa,  1778,  Historia  Naturalis  Testaceorum  Brittanniae,  or  the  British 
Conchology,  p.  168. 

Type  (by  subsequent  designation,  Dali,  1898). — Glycymeris  orbi¬ 
cularis  da  Costa  (=,4rca  glycymeris  Linne).  Recent,  seas  of  Europe. 

The  following  is  a  description  of  the  subgenus  Glycymeris  s.  s.: 

Shell  medium-sized,  suborbicular,  equilateral;  umbos  erect;  sculpture 
consisting  of  radial  striae  or  radial  ribs;  cardinal  area  moderately  wide, 
ligament  amphidetic;  hinge  consisting  of  two  series  of  heavy  teeth,  outer 
teeth  of  both  series  almost  horizontal,  inner  teeth  chevron-shaped,  median 
teeth  obliterated  by  downward  extension  of  cardinal  area;  inner  surface  of 
margin  of  valve  fluted. 

Tertiary  and  living  species  of  Glycymeris,  also  known  as  Pectun- 
culus,  are  most  abundant  in  tropical  and  subtropical  faunas,  but 
occur  in  temperate  faunas. 

Key  to  the  Bowden  species  of  Glycymeris  s.  s. 

Anterior  end  of  shell  obliquely  truncate,  radial  sculpture  weak _ G.  (G.)  jamaicensis 

Anterior  end  of  shell  not  obliquely  truncate,  radial  sculpture  strong. 

G.  (G.)  acuticostata  plasia 

Glycymeris  (Glycymeris)  jamaicensis  Dali. 

(Plate  2,  Figures  1  to  3.) 

Pectunculus  pennacea  Guppy  (not  Lamarck),  1866,  Quart.  Jour.  Geol.  Soc. 
London,  vol.  22,  p.  293. 

Pectunculus  decussatus  Guppy  (part,  not  Linne),  1874,  Geol.  Mag.,  decade  2, 
vol.  1,  p.  443  (list). 

Glycymeris  jamaicensis  Dali,  1898,  Trans.  Wagner  Free  Inst.  Philadelphia, 
vol.  3,  part  4,  p.  608.  Olsson,  1922,  Bull.  Amer.  Paleontology,  vol.  9,  pp. 
350-351,  plate  22,  figs.  3,  4.  Not  Maury,  1917,  Bull.  Amer.  Paleontology, 
vol.  5,  p.  345,  plate  52,  fig.  13  (=G.  difjidentiae  Pilsbry  and  Johnson). 

The  following  is  an  extract  from  the  original  description  of  this 
species : 

Shell  of  moderate  size,  nearly  circular,  quite  convex,  externally  sculptured 
with  fine,  even,  radiating  striae,  impressed  at  intervals  so  as  to  give  the 
effect  of  obsolete  ribs,  which  are  more  apparent  on  the  middle  of  the  shell; 
on  the  beaks  some  of  the  threads  are  stronger;  umbones  low  and  plump; 
cardinal  area  impressed,  narrow,  short,  and  smooth;  teeth  small,  uninter¬ 
rupted,  about  24  in  all,  the  line  gently  arcuate;  inner  margin  fluted,  with 
a  slight  insinuation  near  the  base  in  front. 

Length  35  mm.;  height  33  mm.;  diameter  22  mm. 

Type  locality. — Bowden,  Jamaica. 


PELECYPODS. 


25 


The  following  supplements  the  original  description  of  this  species: 

Shell  inflated,  umbos  low,  full ;  lower  two-thirds  of  anterior  slope  on  adult 
shells  gently  keeled;  at  the  anterior  margin  the  keel  is  the  upper  termina¬ 
tion  of  a  truncation  extending  obliquely  downward;  posterior  half  of  ventral 
margin  symmetrically  curved;  sculpture  consisting  of  many  low,  incon¬ 
spicuous  radial  ribs,  narrowing  into  more  prominent  threads  on  umbo  and 
absent  in  extreme  anterior  and  posterior  dorsal  regions;  fine,  equally  spaced 
radial  striae  and  equally  fine,  but  less  prominent,  concentric  striae  are  super¬ 
imposed  on  the  ribs  and  in  the  narrower  interspaces,  the  two  sets  of  striae 
producing  a  minutely  cancellate  sculpture  visible  only  on  unworn  valves; 
cardinal  area  very  narrow;  hinge-plate  gently  and  uniformly  arched;  teeth 
relatively  small,  13  behind  and  12  in  front  of  umbo;  buttresses  of  muscle- 
scars  not  prominent. 

Length  35  mm.;  height  34  mm.;  diameter  (left  valve)  11.5  mm. 

This  species  is  the  most  abundant  Glycymeris.  Adult  shells  are 
characterized  by  the  anterior  keel  and  anterior  truncation.  Young 
shells  may  readily  be  distinguished  from  the  other  Bowden  species  by 
their  sculpture. 

G.  jamaicensis  closely  resembles  the  living  West  Indian  species  G. 
undatus  Linne,  but  is  smaller  and  has  stronger  radial  ribs  on  the 
upper  half  of  the  shell.  According  to  Olsson,  specimens  of  G. 
jamaicensis  from  Costa  Rica  reach  a  length  of  60  mm.  G.  carbasina 
Brown  and  Pilsbry,  from  the  Gatun  formation  of  the  Canal  Zone,  is 
more  circular  and  has  stronger  radial  sculpture.  The  species  from 
the  Cercado  formation  of  the  Dominican  Republic  ( Axinea  pennacea 
of  Gabb,  Pectuuculus  decussatus  of  Guppy,  and  Glycymeris  jamai¬ 
censis  of  Maury)  has  been  described  by  Pilsbry  and  Johnson  as  G. 
diffidentiae.  It  is  smaller,  less  conspicuously  truncate,  and  has 
stronger  radial  ribs. 

Other  localities . — Miocene,  Curasao.1  Gatun  formation  (middle 
Miocene),  Costa  Rica,  Panama. 

Type  material. — 10  cotypes  (U.  S.  Nat.  Mus.  No.  135762). 

Glycymeris  (Glycymeris)  acuticostata  plaisa,  new  subspecies. 

(Plate  2,  Figures  4,  5.) 

Pectunculus  acuticostatus  Guppy  (not  Sowerby),  1866,  Quart.  Jour.  Geol.  Soc. 

London,  vol.  22,  p.  293,  1866.  Guppy  (part,  not  Sowerby),  1874,  Geol. 

Mag.  decade  2,  vol.  1,  p.  443  (list). 

The  following  is  a  description  of  this  subspecies: 

Shell  medium-sized,  moderately  inflated,  ovate-trigonal;  anterior  margin 
extended,  subangular;  posterior  and  ventral  margins  broadly  rounded; 
umbo  low;  sculpture  consisting  of  about  26  low  radial  ribs,  sharply  angular 
on  unworn  shells  except  in  extreme  anterior  and  posterior  dorsal  parts,  the 
flanks  of  the  ribs  sloping  gently  from  the  angular  summit,  forming  angular 
interspaces;  concentric  sculpture  consisting  of  fine,  equally  spaced  threads, 

1  The  record  of  Bowden  species  from  Curasao  probably  is  incorrect.  Specimens  in  the  United 
States  National  Museum  labeled  “Curacao”  seem  to  be  specimens  from  Bowden.  This  footnote 
was  added  when  the  report  was  in  page  proof. 


26 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


usually  not  overriding  summits  of  radials,  but  conspicuous  on  their  flanks; 
cardinal  area  narrow,  short,  conspicuously  marked  by  ligament  grooves 
diverging  from  a  median  vertical  line;  hinge  plate  arcuate;  teeth  small, 
interrupted  medially  by  the  subsidence  of  the  cardinal  area,  12  or  13  teeth 
in  each  series;  inner  margin  of  the  valve  coarsely  fluted. 

Length  24  mm.;  height  23.8  mm.;  diameter  (left  valve)  6.5  mm. 

The  low  sharply  angular  ribs  and  subangular  anterior  margin  are 
characteristic  features.  On  young  shells  the  irregular  outline  of  the 
anterior  margin  is  obscure  or  absent.  Young  shells  apparently  belong¬ 
ing  to  this  species  have  different  types  of  outline  and  sculpture.  Some 
have  the  typical  somewhat  compressed  outline  and  characteristic 
angular  ribs;  others  are  more  inflated,  and  have  higher  umbos  and 
angular  or  subangular  ribs,  separated  by  definite  interspaces.  Most 
of  the  smallest  shells  are  inflated  and  have  more  or  less  rounded  ribs 
separated  by  narrower  interspaces.  The  shell  of  the  last  group 
resembles  the  living  West  Indian  species  G.  pectinata  (Gmelin),  but 
have  higher  umbos  and  narrower  ribs  and  interspaces. 

G.  acuticostata  plasia  closely  resembles  G.  acuticostata  acuticostata, 
described  by  Sowerby  from  beds  in  the  Dominican  Republic  that  are 
now  known  to  belong  to  the  Gurabo  formation,  but  the  ribs  are 
broader  at  the  base  and  the  interspaces  are  V-shaped. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352737). 

Subgenus  GLYCYMERELLA,  new  subgenus. 

Type. — Pectuneulus  pennacea  Lamarck  (l=Arca  decussatus 
Linne).  Recent,  West  Indies. 

The  following  is  a  description  of  the  subgenus  Glycymerella: 

Shell  medium-sized,  suborbicular,  slightly  inequilateral;  umbos  inflated, 
prosogyrate;  sculpture  consisting  of  narrow  radial  ribs,  radial  striae,  and 
fine  concentric  threads;  cardinal  area  narrow,  excavated;  ligament  opis- 
thodetic;  hinge  consisting  of  two  continuous  series  of  chevron-shaped  teeth, 
posterior  series  convex,  anterior  series  almost  straight,  upper  edge  of  inner 
posterior  teeth  obliterated  by  ligament;  inner  margin  of  valve  fluted. 

The  opisthogyrate  umbos,  opisthodetic  ligament,  and  correspond¬ 
ingly  asymmetric  hinge  separate  Glycymerella  from  Glycymeris  s.  s. 
Glycymerella  resembles  Postligita ,  a  subgenus  of  Glycymeris  de¬ 
scribed  by  Gardner1  for  a  small  Upper  Cretaceous  species,  Glycymeris 
( Postligita )  wordeni  Gardner.  This  species  and  a  similar  unpub¬ 
lished  species  from  the  Upper  Cretaceous  of  Tennessee,  G.  (P.) 
crenata,  Wade,  are  small  and  have  only  concentric  sculpture.  The 
ligament  is  opisthodetic,  like  in  Glycymerella,  but  the  cardinal  area 
is  almost  vertical  and  flat,  and  the  ligament  grooves  are  very  oblique. 
The  hinge  of  Postligita  consists  of  two  uninterrupted  series  of  short 
teeth;  the  lower  teeth  are  chevron-shaped  and  the  upper  ones  are 
straight ;  the  posterior  series  is  convex  and  the  anterior  series  concave. 


1  J.  A.  Gardner,  Maryland  Geological  Survey,  Upper  Cretaceous,  p.  543.  1916. 


PELECYPODS. 


27 


The  hinge  of  Glycymerella  with  its  heavy  chevron-shaped  teeth  is 
more  like  that  of  Glycymeris  s.  s. 

The  Upper  Cretaceous  genus  Protarca  recently  described  by 
Stephenson1  (type,  Protarca  obliqua  Stephenson)  has  a  similar  opis- 
thodetic  ligament  and  hinge,  although  the  teeth  extend  down  to  the 
base  of  the  hinge-plate  and  the  ligament  area  is  deeply  inset.  The 
trigonal  outline  of  the  shell  and  the  smooth  inner  margin  of  Protarca 
also  separate  it  from  Glycymerella . 

Glycymeris  diaphorus  Dali  and  G.  longior  Say,  species  living  on 
the  Atlantic  coast  of  southern  South  America,  have  slightly  twisted 
umbos  and  a  correspondingly  asymmetric  cardinal  area  and  hinge,  but 
these  features  are  not  so  pronounced  as  in  Glycymerella. 

Fossil  and  living  species  of  Glycymerella  seem  to  be  confined  to 
the  West  Indies  and  Central  America.  The  group  first  appears  in 
middle  Miocene  time. 

Glycymeris  (Glycymerella)  prepennacea,  new  species. 

(Plate  2,  Figures  6,  7.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  suborbicular,  inflated;  umbos  low,  strongly  inflated, 
opisthogyrate,  placed  slightly  in  front  of  middle;  lower  anterior  margin 
obscurely  truncated;  sculpture  consisting  of  24  almost  equally  spaced 
primary  radial  ribs,  on  young  shells  sharply  defined  and  narrow,  on  adults 
most  conspicuous  on  the  umbonal  slopes,  becoming  very  low  and  relatively 
broad  distally;  ribs  broader  than  interspaces  and  bearing  a  median  or  sub¬ 
median  groove  on  the  lower  two-thirds;  on  some  shells  secondary  radials 
extend  about  four-fifths  of  distance  from  margin  to  umbo;  concentric  sculp¬ 
ture  consisting  of  fine  striae  impressed  on  the  radials,  producing  a  can- 
cellate  effect;  cardinal  area  narrow,  deeply  excavated,  confined  to  area 
immediately  under  and  behind  umbo;  hinge-plate  gently  arched;  teeth  in 
two  continuous  series,  the  posterior  convex,  including  15  teeth,  the  5  nearest 
the  umbo  vertical  and  small,  due  to  their  upper  part  being  cut  off  by  the 
cardinal  area,  the  remainder  heavier  and  chevron-shaped;  anterior  series 
shorter  and  less  convex,  consisting  of  9  relatively  heavy  teeth,  the  first  3 
(from  the  umbo)  chevron-shaped,  the  remainder  straight  and  almost  hori¬ 
zontal;  muscle  scars  relatively  large,  weakly  buttressed;  inner  margin  of 
the  valve  finely  fluted. 

Length  26  mm.;  height  25.8  mm.;  diameter  (left  valve)  9  mm. 

This  species  is  represented  by  3  left  valves.  The  smallest  shell  has 
radial  sculpture  that  differs  somewhat  from  that  of  the  largest,  as  the 
ribs  are  sharply  defined  and  subangular,  becoming  slightly  broader 
distally;  faint  secondaries  appear  in  the  lower  part  of  some  of  the 
interspaces.  On  the  shell  of  intermediate  size  the  primary  ribs  are 
relatively  broad  and  angular  in  the  lower  part  of  the  shell  and  the 
secondaries  are  of  almost  the  same  size.  On  the  largest  shell  the  ribs 
are  flat,  broad,  and  grooved. 

Glycymeris  ( Glycymerella )  prepennacea  closely  resembles  the 
living  West  Indian  species  called  G.  pennacea  (Lamarck),  but  is 

1  L.  W.  Stephenson,  North  Carolina  Geological  and  Economic  Survey,  vol.  5,  part  1,  pp.  103- 
104.  1923. 


28 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


smaller,  less  truncate  anteriorly,  and  has  fewer  ribs.  The  two  species 
have  the  same  type  of  sculpture.  Large  truncate  specimens  of  G. 
pennacea  have  been  collected  from  Miocene  beds  in  Costa  Rica  and 
described  by  Olsson  as  G.  decussatus  (Linne). 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No. 
352738). 

Genus  ARCA  Linne. 

Subgenus  ARCA  s.  s. 

Linne,  1758,  Systema  Naturae,  ed.  10,  p.  693. 

Type  {by  subsequent  designation,  Gray,  1847). — Area  noae  Linne. 
Recent,  Mediterranean  Sea. 

The  following  is  a  description  of  the  subgenus  Area  s.  s.: 

Shell  usually  large,  elongate,  strongly  inflated,  inequilateral,  posterior 
end  keeled,  middle  part  depressed,  the  depression  coinciding  with  the  wide 
byssal  gape  at  the  ventral  margin;  sculpture  consisting  of  narrow  radial 
ribs,  differing  in  width  and  strength  on  different  parts  of  the  shell;  cardinal 
area  very  wide,  bearing  chevron-shaped  ligament  grooves  that  are  discon¬ 
nected  at  the  apex,  and  fine  striations  perpendicular  to  the  hinge;  hinge 
consisting  of  an  anterior  and  posterior  series  of  teeth,  the  anterior  series 
consisting  of  vertical  or  almost  vertical  teeth,  grading  under  the  umbo 
into  the  smaller  vertical  or  slightly  oblique  teeth  at  the  inner  end  of  the 
posterior  series ;  away  from  the  umbo  the  posterior  teeth  become  larger  and 
more  oblique,  those  near  the  outer  end  chevron-shaped,  those  at  the  inner 
end  consisting  only  of  the  upper  branch  of  the  chevron;  anterior  muscle- 
scar  rounded,  posterior  scar  larger,  rectangular;  inner  ventral  margin  of 
valve  slightly  fluted. 

Cossmann1  has  shown  that  two  groups  are  included  under  Area  s.  s. 
In  the  group  of  A.  noae,  the  ligament  occupies  only  part  of  the  cardi¬ 
nal  area;  in  the  group  of  A.  umbonata  Lamarck  the  ligament  extends 
to  the  outer  edge  of  the  cardinal  area,  occupying  the  entire  area.  In 
the  group  of  A.  noae,  ligament  grooves  extend  to  the  posterior  end  of 
the  ligament  area  and  the  posteriormost  grooves  are  not  paired  with 
anterior  grooves;  but  in  the  group  of  A.  umbonata  the  grooves 
usually  are  confined  to  the  area  under  the  umbo  and  the  posterior  and 
anterior  grooves  are  paired. 

Living  species  of  Area  s.  s.  are  most  abundant  in  the  tropical  seas. 
Most  of  the  Tertiary  species  occur  in  tropical  faunas,  but  are  found 
also  in  subtropical  faunas. 

Key  to  the  Bowden  species  of  Area  s.  s. 

Ligament  grooves  not  confined  to  area  under  umbo .  Group  of  A.  (A.)  occidentals 

Posterior  margin  deeply  emarginate . A.  (A.)  occidentalis 

Ligament  grooves  confined  to  area  under  umbo,  posterior  margin 

truncate  .  Group  of  A.  (A.)  umbonata 

Posterior  end  of  shell  strongly  keeled. 

Sculpture  relatively  coarse .  A.  (A.)  umbonata  morantensis 

Sculpture  fine  . A.  (A.)  bowdeniana 

Posterior  end  of  shell  not  strongly  keeled . A.  (A.)  yaquensis  berryi 


1  M.  Cossmann,  and  A.  Peyrot.  Conch.  Neog.  de  1’ Aquitaine,  vol.  2,  part  1,  p.  140.  1912, 


PELECYPODS. 


29 


Area  (Area)  occidentals  Philippi. 

(Plate  2,  Figures  8,  9.) 

Area  barbadensis  d’Orbigny,  1845  (?),  in  de  la  Sagra,  Hist,  fis.,  polit.  y.  natur. 
de  la  Isla  de  Cuba,  Moluscos,  p.  345  (Spanish  ed.).  1853,  in  de  la  Sagra, 
Hist.  phys.  polit.  et  natur.  de  File  de  Cuba,  Mollusques,  vol.  2,  pp.  321-322 
(French  ed.). 

Area  occidentalis  Philippi,  1847,  Abbild.  u.  Beschreib.,  vol.  3,  p.  29,  plate  4, 
figs.  4a,  4 b,  4c.  Guppy,  1874,  Geol.  Mag.,  decade  2,  vol.  1,  p.  343  (list). 
Guppy,  1876,  Quart.  Jour.  Geol.  Soc.  London,  vol.  32,  p.  531.  Dali,  1898, 
Trans  Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  p.  620.  Dali  and 
Simpson,  1901,  Bull.  U.  S.  Fish  Comm.,  vol.  20,  part  1,  pp.  459-460.  Shel¬ 
don,  1916,  Paleontographica  Americana,  vol.  1,  p.  8,  plate  1,  figs.  8  to  11. 
Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5,  p.  327,  plate  55,  fig.  3.  Olsson, 
1922,  Bull.  Amer.  Paleontology,  vol.  9,  pp.  353-354,  plate  25,  fig.  1. 

Area  noae  Guppy  (not  Linne),  1866,  Quart.  Jour.  Geol.  Soc.  London,  vol.  22, 
p.  293.  Dali  (not  Linne),  1886,  Bull.  Mus.  Comp.  Zool.  Harvard,  vol.  12, 
p.  243. 

The  following  is  the  original  description  of  this  species: 

A.  testa  elongato-oblonga,  subquadrangula ;  latere  antico  breviusulco, 
angulo  fere  recto  terminato;  postico  emarginato;  carina  obtusa  ab  apice 
decurrente;  costis  regularibus,  prominentibus,  interstitia  longitudinaliter 
striata  subaequantibus ;  medianis  parum  minoribus;  area  dorsali  mediocri; 
ligamento  illam  maxima  ex  part  occupante.  Long.  22",  alt.  10",  crass.  11". 

The  following  is  a  description  of  Bowden  specimens  of  this  species: 

Shell  large,  very  inequilateral,  anterior  end  inflated,  posterior  end  higher 
and  compressed;  anterior  part  of  ventral  margin  emarginated  by  a  long 
narrow  byssal  gape,  posterior  part  convex;  posterior  margin  deeply  emargi- 
nate,  the  part  dorsal  to  the  emargination  more  extended;  umbos  situated 
at  about  anterior  fourth  of  length,  broad,  inflated,  slightly  prosogyrate, 
having  a  slight  median  groove,  which  widens  toward  the  ventral  margin 
forming  a  wide,  shallow  depression,  the  limits  of  which  on  the  ventral 
margin  coincide  with  the  limits  of  the  byssal  gape;  posterior  keel  broad; 
radial  sculpture  consisting  of  ribs  of  unequal  size  and  sculpturing  in  differ¬ 
ent  parts  of  the  shell  (anterior  to  the  umbonal  depression  the  ribs  are  high, 
broad,  sharply  sculptured  and  separated  by  narrower  interspaces;  in  the 
wide  depression  they  are  narrow,  low,  and  the  wider  interspaces  contain 
1  to  4  fine  secondary  ribs  that  disappear  on  dorsal  half  of  shell;  posterior 
to  the  depression  the  ribs  are  high  and  broader  and  contain  1  or  2  furrows, 
the  equally  wide  interspaces  containing  2  to  5  secondary  ribs;  the  ribs  on 
the  posterior  keel  are  low  and  divided  ventrally  by  furrows  into  parts  of 
irregular  width;  above  the  posterior  keel  the  first  3  ribs  are  broad  and 
usually  furrowed,  but  the  other  ribs  are  narrow) ;  concentric  sculpture  con¬ 
sisting  of  irregular  growth  lines  on  both  ribs  and  interspaces;  cardinal  area 
wide  and  long,  ligament  not  extending  to  outer  edge  of  area;  ligament 
grooves  not  connected  at  apex,  the  posteriormost  grooves  not  paired  with 
anterior  grooves;  hinge  long  and  straight;  teeth  numerous,  becoming  longer 
and  slightly  oblique  at  the  ends;  anterior  and  posterior  inner  margin 
strongly  fluted,  ventral  margin  along  byssal  gape  smooth ;  behind  the  byssal 
gape  the  margin  is  weakly  fluted. 

Length  68  mm. ;  maximum  height  28  mm. ;  diameter  (left  valve)  15  mm. 

The  shape  is  variable  with  regard  to  details,  but  the  general  pro¬ 
portions  and  sculpture  are  uniform.  The  length  of  the  two  posterior 


30 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


“wings”  and  the  depth  of  the  emargination  between  them  are  very 
variable. 

This  species  apparently  is  the  shell  that  Petiver  called  “Mytilus 
Barbadensis,  vulgaris,  striatus,  striis  fuscis,”  cited  by  Sloane  in  his 
Natural  History  of  Jamaica.1  This  name  was  given  binomial  stand¬ 
ing  by  d’Orbigny  in  his  work  on  the  mollusks  of  Cuba.  As  there  is 
some  uncertainty  concerning  the  date  of  publication  of  the  two 
editions  of  d’Orbigny’s  report,  it  is  not  known  whether  d’Orbigny’s  or 
Philippi’s  name  has  the  right  of  priority.  The  date  given  on  the  title- 
page  of  the  Spanish  edition  is  1845,  but  in  the  text  the  author  refers 
to  publications  that  did  not  appear  until  1846.  If  this  edition  was 
published  in  parts,  like  the  French  edition,  the  Areas  probably  were 
included  in  the  last  part.  Although  the  date  of  the  French  edition 
usually  is  given  as  1853,  the  parts  appeared  at  different  times  and 
the  one  containing  the  Areas  probably  was  published  about  1847. 
Although  d’Orbigny  did  not  figure  A.  barbadensis ,  there  is  no  doubt 
concerning  it,  as  he  stated  that  it  was  the  shell  that  had  been  con¬ 
fused  with  the  Mediterranean  A.  noae.  Until  more  definite  informa¬ 
tion  is  available  it  seems  advisable  to  retain  Philippi’s  name. 

Other  localities. — Gurabo  formation  (middle  Miocene),  Dominican 
Republic.  Gatun  formation  (middle  Miocene),  Costa  Rica.  Caloosa- 
hatchee  marl  (Pliocene),  Florida.  Pleistocene,  Florida  Keys,  West 
Indies.  Living  in  the  Gulf  of  Mexico  and  the  West  Indies,  northward 
to  Hatteras  and  eastward  to  Bermuda,  in  12  to  20  fathoms. 

Area  (Area)  umbonata  morantensis,  new  subspecies. 

(Plate  2,  Figures  10,  11.) 

The  following  is  a  description  of  this  subspecies: 

Shell  small,  subrhomboidal;  ventral  margin  slightly  emarginated  by  the 
short  byssal  gape;  posterior  margin  obliquely  truncated;  umbos  prominent, 
strongly  incurved,  placed  at  about  anterior  third  of  length  of  hinge;  surface 
in  front  of  posterior  keel  sculptured  with  radial  ribs  that  are  relatively 
coarse  except  in  region  of  byssal  gape;  on  the  anterior  half  of  the  shell 
1  or  2  fine  ribs  lie  in  the  interspaces;  the  radial  ribs  are  crossed  by  weaker 
low  irregular  concentric  threads,  producing  an  obscurely  imbricate  sculp¬ 
ture;  behind  the  posterior  keel  there  are  3  or  4  coarse  obscurely  beaded 
ribs,  followed  by  several  finer  ribs;  cardinal  area  wide,  bearing  several 
paired  unconnected  ligament  grooves;  inner  margin  of  valve  smooth  except 
at  posterior  end. 

Length  18  mm.;  maximum  height  8.5  mm.;  diameter  (left  valve)  5.8  mm. 

All  the  Bowden  shells  are  much  smaller  than  the  living  West 
Indian  A.  umbonata  umbonata,  and  are  more  elongate  and  have 
coarser  sculpture  than  living  shells  of  the  same  size.  The  shells  from 
the  Tampa  formation  and  Chipola  formation  of  Florida,  and  the 

Voyage  to  the  islands  Madeira,  Barbados,  Nieves,  St.  Christopher,  and  Jamaica;  with  the 
Natural  History  ...  of  the  last  of  these  islands,  vol.  2,  p.  257,  No.  9.  1725. 


PELECYPODS. 


31 


Cercado  formation  of  the  Dominican  Republic  called  A.  umbonata 
are  more  similar  to  living  shells. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352740). 

Area  (Area)  bowdeniana  Dali. 

(Plate  3,  Figures  1  to  4.) 

Area  bowdeniana  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3, 
part  4,  pp.  622-623,  plate  33,  fig.  12.  Sheldon,  1916,  Paleontographica 
Americana,  vol.  1,  p.  11,  plate  2,  fig.  3. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  inflated,  somewhat  irregular,  very  inequilateral,  the  beaks 
almost  posterior;  dorsal  slope  conspicuous;  its  outer  border  with  a  stout 
keel  and  its  surface  somewhat  excavated;  beaks  small,  pointed,  prosogyrate; 
cardinal  area  wide,  lozenge-shaped,  flattish,  with  a  few  grooves  for  the 
resilium  forming  a  small  lozenge  near  the  beaks;  sculpture  as  in  A.  umbo¬ 
nata,  the  imbrications  close  and  subnodulous;  shell  not  alate  in  front  and 
with  the  anterior  margin  nearly  vertical  from  the  hinge-line;  posterior 
end  obliquely  truncate,  the  basal  angle  most  extended,  the  dorsal  one 
forming  nearly  a  right  angle;  anterior  teeth  10,  posterior  27,  with  no  notice¬ 
able  hiatus  in  the  line,  the  teeth  resembling  those  of  A.  paratina  but  pro¬ 
portionately  larger;  interior  smooth,  the  posterior  end  with  a  few  flutings, 
the  rest  of  the  margin  entire;  the  byssal  foramen  narrow  and  its  margin 
encroaching  only  moderately  on  the  valves.  Lon.  15,  alt.  of  hinge-line  6,  of 
beaks  8,  diam.  (greatest  posteriorly)  9  mm. 

r 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

The  umbos  are  anterior  in  position,  lying  at  about  the  anterior  third  of 
the  length  of  the  hinge.  The  sculpture  is  fine.  In  front  of  the  posterior 
keel  the  imbricate  or  cancellate  effect  is  produced  by  the  superposition  of 
strong,  somewhat  irregular  concentric  threads  on  weaker  radial  ribs;  above 
the  posterior  keel  there  are  about  3  strong  radial  ribs,  on  which  the  con¬ 
centric  ridges  are  weak,  followed  by  2  or  3  narrow  ribs.  There  is  only  one 
pair  of  subumbonal  ligament  grooves. 

The  largest  valve  has  the  following  dimensions:  length  17  mm., 
height  8.5  mm.,  diameter  (right  valve)  4.5  mm.  The  outline  and 
proportions  of  shape  are  irregular,  but  certain  features,  including  the 
sharpness  of  the  posterior  keel,  depth  of  excavation  of  the  region 
above  the  keel,  and  the  fine  obscurely  imbricate  sculpture  are  con¬ 
spicuous  on  all  shells  of  this  species. 

A.  bowdeniana  closely  resembles  A.  umbonata  morantensis,  but  is 
smaller  and  usually  less  inflated ;  has  slightly  more  prosogyrate  beaks, 
finer  sculpture,  larger  teeth,  somewhat  narrower  cardinal  area,  and 
stronger  posterior  keel.  Perhaps  the  most  striking  difference  lies  in 
the  diameter  of  different  parts  of  the  shell.  The  maximum  diameter 
of  A.  bowdeniana  is  at  about  the  middle,  that  is,  behind  the  beaks, 
and  rapidly  decreases  anteriorly  across  the  beaks  to  the  anterior 
margin;  whereas  A.  umbonata  morantensis  has  the  greatest  diameter 


32 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


at,  or  just  behind,  the  beaks  and  the  reduction  in  diameter  anteriorly 
to  the  margin  is  even  more  rapid. 

A  right  valve  of  A.  bowdeniana  from  Limon,  Costa  Rica  (U.  S. 
Nat.  Mus.  No.  135652)  has  a  more  angular  keel  and  finer  sculpture 
than  specimens  from  Bowden. 

Other  localities. — Gatun  formation  (middle  Miocene),  Costa  Rica. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
61621). 

Area  (Area)  yaquensis  berryi,  new  subspecies. 

(Plate  3,  Figures  5,  6.) 

The  following  is  a  description  of  this  subspecies: 

Shell  very  small,  elongate,  moderately  inflated,  trapezoidal;  ventral 
margin  slightly  contracted  medially  by  the  short,  narrow  byssal  gape; 
umbos  placed  at  about  anterior  third  of  length;  posterior  ridge  low;  sculp¬ 
ture  consisting  of  many  clear-cut,  rounded  radial  ribs,  very  narrow  in 
middle  part  of  shell  and  widest  in  extreme  anterior  and  posterior  parts; 
the  ribs  may  be  finely  and  faintly  beaded  by  numerous  low  concentric 
threads;  cardinal  area  wide,  containing  a  single  pair  of  fine  ligament  grooves 
diverging  from  the  umbo  at  an  acute  angle;  hinge  almost  as  long  as  shell, 
straight;  teeth  uninterrupted  medially,  fine,  numerous;  inner  margin  of 
shell  deeply  fluted  except  in  median  ventral  part. 

Length  10  mm.;  height  5  mm.;  diameter  (right  valve)  2  mm.;  length  of 
hinge  7  mm. 

This  small  species  is  the  most  abundant  Area  s.  s.  Some  shells  are 
low  and  elongate,  others  are  higher,  shorter,  and  more  inflated.  The 
radial  ribs  may  be  flat  and  low  instead  of  round  and  high.  On  some 
shells  the  ribs  are  grooved  and  in  the  middle  part  of  the  valve 
secondary  ribs  may  lie  in  the  interspaces. 

A.  yaquensis  berryi  is  much  smaller  than  any  other  Bowden  species 
of  Area  s.  s.  It  differs  from  young  shells  of  A.  occidentalis,  A. 
umbonata  morantensis ,  and  A.  bowdeniana  in  the  absence  of  a  sharp 
posterior  keel,  as  well  as  in  outline  and  sculpture.  A.  yaquensis  berryi 
closely  resembles  A.  yaquensis  yaquensis  Maury,  described  from  the 
Cercado  formation  of  the  Dominican  Republic,1  but  is  more  obliquely 
truncated  posteriorly,  and  has  wider  ribs  between  the  posterior  ridge 
and  middle  of  the  shell  and  less  distinct  concentric  sculpture.  A 
similar  small  Area,  called  A.  yaquensis  Maury  by  Hubbard,  occurs  in 
Porto  Rico  in  beds  ranging  in  age  from  the  Lares  limestone  (middle 
or  upper  Oligocene)  to  the  Quebradillas  limestone  (lower  Miocene). 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352742). 

v 


1  The  U.  S.  Geological  Survey  party  collected  this  species  also  from  the  Gurabo  formation. 


PELECYPODS. 


33 


Genus  BARBATIA  Gray. 

Subgenus  BARBATIA  s.  s. 

Section  BARBATIA  s.  s. 

Gray,  1847,  Proceedings  Zoological  Society  of  London,  part  15,  p.  197. 

Type  ( by  original  designation). — Area  barbata  Linne.  Recent, 
Mediterranean  Sea. 

The  following  is  a  description  of  the  section  Barbatia  s.  s.: 

Shell  usually  large,  inequilateral,  moderately  inflated,  posterior  slope 
rounded,  byssal  gape  narrow;  sculpture  consisting  of  narrow  radial  riblets; 
cardinal  area  narrow,  bearing  5  or  more  ligament  grooves,  the  anterior 
ones  shorter  than  the  posterior,  meeting  under  the  umbo  at  an  obtuse  angle ; 
on  adult  shells  a  narrow  area  in  front  of  the  umbo  has  no  grooves,  on  young 
shells  this  area  extends  back  of  the  umbo  and  occupies  the  entire  width 
of  the  cardinal  area;  hinge  consisting  of  two  series  of  teeth,  continuous 
on  young  shells,  separated  by  an  endentulous  gap  on  adult  shells;  anterior 
series  short,  consisting  of  heavy  chevron-shaped  teeth,  the  lower  branch 
shorter  than  the  upper,  the  outermost  teeth  consisting  of  only  the  oblique 
upper  branch ;  anterior  series  terminating  under  umbo ;  posterior  series  long, 
teeth  under  umbo  short,  vertical  or  slightly  oblique,  effaced  on  adults, 
outer  teeth  resembling  those  in  anterior  series;  ventral  margin  of  valve 
finely  fluted. 

Barbatia  is  here  used  as  a  genus  including  all  Areas  having  a  rela¬ 
tively  narrow  cardinal  area  bearing  chevron-shaped  ligament  grooves. 
The  separation  of  the  hinge  into  an  anterior  and  posterior  series  is 
more  pronounced  than  in  Area  s.  s.;  the  cardinal  area  is  narrower; 
the  ligament  grooves  meet  at  a  more  obtuse  angle;  and  the  byssal 
gape  is  narrower. 

The  Bowden  shells  here  placed  in  the  section  Barbatia  s.  s.  usually 
have  been  placed  in  Calloarca  Gray.  The  type  of  Calloarca,  Area 
alternata  Sowerby,  a  living  species  from  the  Pacific  coast  of  Central 
America,  has  a  shorter  anterior  series  of  teeth  and  an  angular 
posterior  ridge.  Calloarca  is  here  considered  a  section  of  the  sub¬ 
genus  Barbatia,  differing  only  in  details  from  Barbatia  s.  s. 

Living  Barbatias  are  most  abundant  in  the  tropical  seas,  but  range 
into  subtropical  and  temperate  regions.  They  have  a  long  history 
and  species  are  found  in  most  of  the  Tertiary  faunas  of  the  world. 

Key  to  the  Bowden  species  of  Barbatia  s.  s. 


Byssal  gape  narrow. 

Length  of  adult  shell  exceeding  15  mm . B .  ( B .)  islopa 

Length  of  adult  shell  not  exceeding  15  mm. 

Shell  high .  B.  ( B .)  propertua 

Shell  elongate. 

Ribs  beaded .  B.  ( B .)  delepida 

Ribs  not  beaded .  B.  ( B .)  endomena 

Byssal  gape  wide .  B.  (B.)  inusitata 


34 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Barbatia  (Barbatia)  islopa,  new  species. 

(Plate  3,  Figures  7,  8.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  moderately  inflated,  elongate,  subtrapezoidal ;  ante¬ 
rior  margin  asymmetrically  rounded;  posterior  margin  truncated  above, 
acutely  extended  below;  posterior  slope  rounded;  umbo  low,  lying  at 
about  anterior  fourth  of  length;  sculpture  consisting  of  numerous,  closely 
spaced  radial  ribs  of  different  width,  narrowest  in  central  part  of  shell; 
some  interspaces  in  central  part  of  shell  contain  secondary  riblets;  ribs 
usually  beaded  at  irregular  intervals;  ribs  widest  and  strongest,  interspaces 
widest,  and  beads  most  prominent  on  and  behind  posterior  slope;  cardinal 
area  moderately  narrow,  containing  ligament  grooves  that  diverge  from 
under  umbo  at  an  obtuse  angle. 

Length  26.5  mm.;  height  13  mm.;  diameter  (right  valve)  5.8  mm.;  length 
of  hinge  15  mm. 

Most  of  the  shells  are  much  smaller  than  the  holotype.  This 
species  resembles  the  living  West  Indian  species  that  is  known  as 
“Area  Candida  Gmelin,”  but  is  much  smaller,  more  elongate,  and  less 
inflated. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352743). 


Barbatia  (Barbatia)  propertua,  new  species. 

(Plate  3,  Figures  9,  10.) 

The  following  is  a  description  of  this  species: 

Shell  small,  heavy,  posterior  end  extended  below,  subrounded  above; 
umbo  full,  high,  and  broad;  posterior  slope  rounded;  ventral  half  of  shell 
bearing  a  slight  median  depression;  sculpture  consisting  of  numerous  fine 
radial  ribs  separated  by  narrow  interspaces,  except  on  the  posterior  slope, 
where  the  ribs  are  wider  and  the  interspaces  of  about  the  same  width;  some 
of  the  ribs  are  grooved;  concentric  sculpture  indicated  by  beads  on  the 
ribs;  cardinal  area  moderately  narrow,  bearing  transvere  striations;  inner 
margin  of  valve  not  definitely  fluted. 

Length  8  mm.;  height  5.8  mm.;  diameter  (right  valve)  1.8  mm.;  length 
of  hinge  4.5  mm. 

The  small  right  valve  on  which  the  description  is  based  probably 
is  not  full  grown,  as  there  are  no  recognizable  ligament  grooves.  The 
cardinal  area  is  wider  and  the  posterior  slope  more  rounded  than  in 
the  section  Acar. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352744). 

Barbatia  (Barbatia)  delepida,  new  species. 

(Plate  3,  Figures  11,  12.) 

The  following  is  a  description  of  this  species: 

Shell  small,  base  almost  straight,  its  middle  part  slightly  emarginate; 
posterior  margin  extended  below,  obliquely  truncated  above;  umbo  broad; 


PELECYPODS. 


35 


posterior  slope  rounded;  sculpture  consisting  of  numerous  fine  radial  ribs, 
ornamented  with  conspicuous,  delicately  sculptured,  square  or  slightly 
elongate  beads;  as  usual,  the  ribs  and  interspaces  are  wider  at  the  anterior 
and  posterior  ends,  especially  on  the  posterior  slope;  cardinal  area  wide 
for  size  of  shell,  containing  obscure  transverse  striations  in  anterior  and 
middle  parts  and  deeper  oblique  ligament  grooves  at  posterior  end ;  anterior 
and  posterior  inner  margins  obscurely  fluted. 

Length  6.5  mm.;  height  4.2  mm.;  diameter  (left  valve)  1.8  mm.;  length 
of  hinge  5  mm. 

The  delicate  reticulate  sculpture  is  the  prominent  feature  of  this 
species,  which  also  is  represented  only  by  a  small  probably  immature 
valve.  It  resembles  B.  propertua  but  is  more  rectangular  and  has 
more  delicate  and  more  uniform  sculpture,  and  wider  cardinal  area. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352745). 

Barbatia  (Barbatia)  endomena,  new  species. 

(Plate  3,  Figures  13,  14.) 

The  following  is  a  description  of  this  species: 

Shell  small,  elongate,  subtrapezoidal,  inflated;  dorsal  and  ventral  margins 
subparallel;  posterior  end  truncated;  umbo  full,  broad,  lying  at  about 
anterior  third  of  length;  posterior  slope  round;  sculpture  consisting  of 
numerous  radial  ribs;  extreme  anterior  ribs  separated  by  interspaces  of 
virtually  the  same  width,  following  ribs  narrower,  the  interspaces  wider  than 
the  ribs  and  containing  a  fine  secondary  rib ;  towards  the  posterior  slope  the 
ribs  are  wider  and  separated  by  narrow  grooves;  on  the  posterior  slope 
the  ribs  are  few  and  broad  and  the  interspaces  are  of  about  the  same  width; 
ribs  bearing  obscure  elevations  along  concentric  lines,  except  on  anterior 
part  of  shell,  where  the  concentric  sculpture  forms  definite  beads;  cardinal 
area  moderately  wide,  posterior  part  containing  oblique  ligament  grooves; 
posterior  and  anterior  inner  margins  obscurely  fluted. 

Length  10  mm.;  height  5.5  mm.;  diameter  (right  valve)  2.5  mm.;  length 
of  hinge  6.5  mm. 

B.  endomena  is  known  from  a  small  valve  that  may  not  be  full 
grown.  The  outline  of  the  shell  suggests  the  section  ^4car,  but  the 
cardinal  area  is  wider  than  in  ^4car  and  the  posterior  slope  more 
rounded.  It  is  more  elongate  and  more  inflated  than  young  shells  of 
B.  islopa  of  the  same  size,  and  has  higher  umbos  and  less  conspicuous 
concentric  sculpture. 

Type  material. — Llolotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352746). 


Barbatia  (Barbatia)  inusitata,  new  species. 

(Plate  3,  Figures  15,  16.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  high,  somewhat  compressed,  outline  irregular;  poste¬ 
rior  margin  obliquely  truncated  above,  extended  below;  anterior  part  of 
the  ventral  margin  distorted  by  the  long,  wide  byssal  gape ;  umbos  relatively 
low,  broad,  lying  at  about  anterior  third  of  length;  posterior  ridge  promi- 


36 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


nent,  region  behind  ridge  excavated;  radial  sculpture  consisting  of  numerous 
narrow,  irregular  ribs;  some  of  the  ribs  are  grooved  and  a  few  interspaces 
bear  narrower  secondary  ribs;  interspaces  usually  narrower  than  ribs; 
posterior  slope  sculptured  with  4  ribs  much  coarser  than  the  others;  con¬ 
centric  sculpture  consisting  of  irregular  growth-lines  and  occasional  threads, 
producing  in  certain  parts  of  shell  obscure  reticulate  sculpture;  cardinal 
area  relatively  short  and  wide,  conspicuously  marked  by  6  or  7  concentric 
ligament  grooves  that  diverge  at  a  wide  angle ;  hinge  gently  arched ;  anterior 
teeth  chevron-shaped,  median  teeth  very  short,  posterior  teeth  large, 
oblique;  inner  margin  of  shell  faintly  fluted. 

Length  31.5  mm.;  height  22  mm.;  diameter  (right  valve)  7.8  mm.;  length 
of  hinge  12  mm. 

B.  inusitata  has  a  wider  byssal  gape  and  wider  cardinal  area  than 
the  type  species  of  Barbatia.  Its  irregular  distorted  shape,  promi¬ 
nent  byssal  gape  and  excavated  posterior  slope  are  characteristic 
features.  Several  similar  species  have  been  described,  such  as  B. 
irregularis  Dali,  from  the  Tampa  formation  of  Florida,  and  B . 
rnarylandica  (Conrad),  from  the  upper  Miocene  formations  of  Mary¬ 
land  and  the  lower  Miocene  Chipola  marl  of  Florida. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 

‘  352747). 


Section  ACAR  Gray. 

Gray,  1887,  Annals  and  Magazine  of  Natural  History,  ser.  2,  vol.  19,  p.  369. 

Type. — Area  gradata  Broderip  and  Sowerby.  Recent,  Pacific 
coast  of  Mexico  and  Central  America. 

The  following  is  a  description  of  the  section  Acar: 

Shell  medium-sized,  trapezoidal,  posterior  end  keeled;  byssal  gape  nar¬ 
row;  sculpture  coarsely  reticulate  and  imbricate;  cardinal  area  narrow 
behind  umbo,  wider  in  front  of  umbo,  ligament  confined  to  narrow  area 
behind  umbo ;  ligament  grooves  slightly  bent  behind  umbo ;  teeth  resembling 
those  of  Barbatia  s.  s.,  but  the  anterior  series  are  longer;  ventral  margin 
fluted,  except  at  byssal  gape. 

Gray  included  the  following  3  species  under  Acar  without  designat¬ 
ing  a  type;  B.  ( arbatia )  reticulata ,  B.  divaricata,  and  B.  gradata. 
The  name  Area  reticulata  was  first  given  binomial  standing  by 
Gmelin,1  who  referred  to  figures  given  by  Lister,  Martini,  and  Chem¬ 
nitz.  The  name  has  commonly  been  accepted  for  the  shell  that 
Chemnitz2  figured.  Chemnitz  gave  the  West  Indies  as  the  probable 
locality,  but  Kobelt3  states  that  the  shell  figured  by  Chemnitz  came 
from  the  Indian  Ocean.  The  figure  does  not  resemble  the  West 
Indian  Area  that  goes  under  the  name  of  reticulata.  Sowerby4  de- 

1  Gmelin.  Syst.  Nat.,  ed.  12,  vol.  6,  p.  3311.  1792. 

3  J.  H.  Chemnitz.  Neus  Syst.  Conch.-Cab.,  vol.  7,  pp.  193-194,  plate  54,  fig.  540.  1784. 

3  W.  Kobelt.  Syst.  Conch.-Cab.  von  Martini  und  Chemnitz:  Band  8,  Abtheilung  2,  Die 

Gattung  Area  L.,  p.  211.  1891. 

4  G.  B.  Sowerby.  Proc.  Zool.  Soc.  London,  pt.  1,  p.  18.  1833. 


PELECYPODS. 


37 


scribed  Byssoarca  divaricata  from  “Annaa  or  Chain  Island”  in  the 
East  Indies.  Area  gradata  was  described  by  Broderip  and  Sowerby1 
from  Mazatlan  on  the  Pacific  coast  of  Mexico. 

Several  writers  have  cited  A.  donaeijormis  Reeve  as  the  type  of 
Acar,  because  Fischer2  gave  it  as  an  example  of  Acar.  Apparently  no 
type  from  the  original  list  has  been  designated.  A.  gradata  Broderip 
and  Sowerby  is  herewith  designated  the  type,  as  it  is  the  best  known 
of  the  three  species.  Some  writers  consider  A.  gradata  identical  with 
the  West  Indian  species  known  as  A.  reticulata. 

The  hinge  and  cardinal  area  of  Acar  resemble  those  of  young 
specimens  of  Barbatia  barbata  of  the  same  size,  but  the  ligament  area 
is  narrower.  The  imbricate  sculpture  is  a  striking  feature. 

There  are  only  a  few  Tertiary  and  living  species  of  Acar.  Both 
the  living  and  fossil  species  are  found  only  in  tropical  or  subtropical 
faunas. 


Barbatia  (Acar)  domingensis  (Lamarck). 

(Plate  3,  Figures  17,  18.) 

Area  domingensis  Lamarck,  1819,  Hist.  Nat.  des  Anim.  sans.  Vert.,  vol.  6,  p.  40. 

Area  squamosa  Guppy  (not  Lamarck),  1874,  Geol.  Mag.,  decade  2,  vol.  1, 
p.  443  (list). 

Area  reticulata  Dali  (not  Chemnitz),  1886,  Bull.  Mus.  Comp.  Zool.  Harvard, 
vol.  12,  p.  242.  Dali  (not  Gmelin,  1889,  U.  S.  Nat.  Mus.  Bull.  37,  p.  42. 
Dali  and  Simpson  (not  Gmelni),  1901,  U.  S.  Fish  Comm.  Bull.,  vol.  20, 
part  1,  p.  460.  Sheldon  (not  Gmelin),  1916,  Paleontographica  Americana, 
vol.  1,  p.  20,  pi.  4,  figs.  8-12. 

Barbatia  (Acar)  reticulata  Dali  (not  Gmelin),  1898,  Trans.  Wagner  Free  Inst. 
Sci.,  Philadelphia,  vol.  3,  part  4,  p.  629.  Dali  (not  Gmelin),  1915,  U.  S. 
Nat.  Mus.  Bull.  90,  p.  120.  Maury  (not  Gmelin),  1917,  Bull.  Amer.  Pal., 
vol.  5,  p.  330,  plate  30,  fig.  16.  Maury  (not  Gmelin),  1920,  Scientific 
Survey  of  Porto  Rico  and  the  Virgin  Islands,  vol.  3,  part  1,  pp.  7-8,  N.  Y. 
Acad.  Sci.  Hubbard  (not  Gmelin),  1921,  Scientific  Survey  of  Porto  Rico 
and  the  Virgin  Islands,  vol.  3,  part  2,  p.  106,  N.  Y.  Acad.  Sci. 

The  following  is  the  original  description  of  this  species: 

A.  testa  transversim  oblonga,  decussatim  striata;  antico  latere  producto, 
subacuto,  granoso;  natibus  approximatis. 

Habite  l’Ocean  des  Antilles,  a  S-Domingue. 

The  following  is  a  description  of  Bowden  specimens  of  this  species : 

Shell  small,  thick,  subrhomboidal,  moderately  inflated;  posterior  end 
obliquely  truncated;  umbos  low,  broad,  strongly  incurved,  placed  at  about 
anterior  third  of  length;  posterior  keel  subangular;  sculpture  consisting  of 
strong,  somewhat  irregular  concentric  ridges,  separated  by  deeply  chan¬ 
neled  narrow  grooves,  and  less  prominent,  but  more  numerous,  radial  ribs; 
the  concentric  ridges  often  give  an  imbricate  effect,  especially  on  the 
posterior  ridge,  and  some  ridges  bear  fine  concentric  striae;  posterior  slope 
less  strongly  sculptured;  cardinal  area  narrow,  excavated,  wider  in  front 

1  W.  J.  Broderip  and  G.  B.  Sowerby.  Zool.  Jour.,  vol.  4,  pp.  365-366.  1829. 

2  P.  Fischer.  Man.  Conch.,  p.  975.  1887. 


38 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


of  umbo,  part  behind  umbo  bearing  slightly  oblique  grooves;  muscle  scars 
prominent,  the  edges  raised  above  surface  of  shell;  inner  margin  of  the 
valves  finely  and  irregularly  fluted. 

Length  19  mm.;  height  11  mm.;  diameter  (left  valve)  5  mm.;  length  of 
hinge  10  mm. 

According  to  the  evidence  discussed  on  page  36,  it  seems  that 
Gmelin’s  name  is  not  available  for  this  common  West  Indian  species, 
and  consequently  Lamarck’s  name  is  adopted. 

This  species,  which  has  an  extended  geological  range  in  the  West 
Indies  and  regions  nearby,  is  represented  by  many  specimens  in  the 
collections  from  Bowden,  but  none  is  so  large  as  some  of  the  living 
ones.  The  shape  and  peculiar  half-imbricate  and  reticulate  sculpture 
alone  distinguish  it  from  the  other  Bowden  Areas. 

Other  localities. — Tampa  formation  (lower  Miocene),  Florida. 
Ponce  chalky  beds  (lower  Miocene),  Porto  Rico.  Chipola  formation 
(lower  Miocene),  Florida.  Cercado  formation  (lower  Miocene), 
Dominican  Republic.  Quebradillas  limestone  (lower  Miocene),  Porto 
Rico.  Miocene  (?),  Matura,  Trinidad.  Caloosahatchee  marl  (Plio¬ 
cene),  Florida.  Pleistocene,  West  Indies.  Living  in  West  Indies, 
northward  to  Hatteras  and  eastward  to  Bermuda,  in  shallow  water. 

Subgenus  OBLIQUARCA  Sacco. 

Sacco,  1898,  I  Molluschi  dei  Terreni  Terziarii  del  Piemonte  e  della  Liguria, 
part  26,  p.  16. 

Type  (by  original  designation). — Area  modioliformis  Deshayes. 
Eocene,  Paris  Basin. 

The  following  is  a  description  of  the  subgenus  Obliquarca : 

Shell  small,  subovate,  moderately  inflated,  very  inequilateral;  umbos 
almost  terminal,  prosogyrate;  sculpture  consisting  of  fine,  slightly  beaded 
radial  ribs;  cardinal  area  very  narrow,  part  behind  umbo  marked  by  wide 
deep  ligament  grooves  separated  by  narrow  sharp-edged  ridges,  part  in 
front  of  umbo  more  elevated  and  longitudionally  striate;  hinge  consisting 
of  two  series  of  teeth,  anterior  series  comprising  a  few  heavy  oblique  teeth, 
posterior  series  comprising  a  large  number  of  teeth  that  are  small  and 
vertical  at  anterior  end  of  series,  and  larger  and  oblique  at  posterior  end; 
on  some  shells  the  two  series  are  separated  by  an  edentulous  gap  due  to  the 
lowering  of  the  ligament;  posterior  muscle-scar  slightly  larger  than  the 
anterior;  ventral  margin  of  valve  smooth. 

The  division  of  the  hinge  into  an  anterior  and  posterior  series  is 
more  pronounced  than  in  the  subgenus  Barbatia  s.  s.,  but  the  cardinal 
area  is  essentially  the  same  as  in  young  specimens  of  Barbatia  barbata. 

All  the  Bowden  species  of  Obliquarca  have  a  smaller  and  heavier 
series  of  anterior  teeth  than  the  type  species.  Only  1  Bowden  species, 
A.  modiolida,  is  modioloid  like  the  type  species,  and  has  an  even 
narrower  cardinal  area  than  the  type  species.  The  other  2  species, 
especially  0.  subcandida,  resemble  Barbatia  externally,  but  they  are 
Obliquarcas  in  the  features  of  the  hinge  and  cardinal  area. 


PELECYPODS.  39 

Obliquarcas  heretofore  were  known  only  from  Eocene  beds  of  the 
Paris  Basin  and  southern  Europe  and  late  Tertiary  deposits  of  the 
Mediterranean  region.  Some  of  the  living  tropical  Barbatias  may  be 
Obliquarcas,  as  Cossmann  has  suggested. 

Key  to  the  Bowden  species  of  Ohliquarca. 

Outline  not  modioloid. 

Shell  strongly  inflated 
Shell  weakly  inflated . 

Outline  modioloid . 


. . .  B.  (0.)  dentera 
B.  (0.)  sub  Candida 
B.  (0.)  modiolida 


Barbatia  (Obliquarca)  dentera,  new  species. 

(Plate  3,  Figures  19,  20.) 

The  following  is  a  description  of  this  species: 

Shell  small,  strongly  inflated,  very  inequilateral;  posterior  end  extended 
and  abruptly  rounded,  base  gently  arcuate;  umbos  full,  broad,  placed  almost 
at  anterior  fifth  of  length;  posterior  ridge  broad  and  low;  radial  sculpture 
consisting  of  numerous  narrow,  weakly  sculptured  ribs  of  varying  width, 
widest  at  posterior  end ;  concentric  sculpture  consisting  of  irregularly  spaced 
incrementals,  slightly  beading  the  radial  ribs;  cardinal  area  narrow,  part 
behind  umbo  depressed  and  crossed  by  wide,  deep  ligament  grooves;  part 
under  umbo  elevated  and  horizontally  striate;  anterior  series  of  teeth  con¬ 
sisting  of  6  thickened  irregular  teeth  placed  under  umbo,  the  thickened  area 
ceasing  abruptly  behind  the  umbo,  followed  by  the  posterior  series,  con¬ 
sisting  of  23  teeth  which  increase  in  size  toward  outer  end  and  at  the  end 
become  oblique. 

Length  16  mm.;  height  10.5  mm.;  diameter  (left  valve)  4.1  mm.;  length 
of  hinge  9  mm. 

The  holotype  is  the  only  specimen  of  this  species.  The  shape  and 
sculpture  suggest  Barbatia  s.  s. 

Type  material . — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352749). 

Barbatia  (Obliquarca)  subcandida,  new  species. 

(Plate  3,  Figures  21,  22.) 

The  following  is  a  description  of  this  species: 

Shell  small,  subovate,  slightly  inflated;  posterior  end  higher;  anterior  end 
subtruncated;  ventral  margin  sloping  gently  downward  toward  posterior 
end;  umbo  low  and  flat,  lying  at  about  anterior  fifth  of  length;  posterior 
ridge  low  and  broad  in  umbonal  region,  disappearing  toward  lower  margin; 
radial  sculpture  consisting  of  numerous  fine  ribs,  narrowest  in  the  part 
below  the  umbo  and  widest  at  posterior  end;  ribs  separated  by  fine  grooves, 
except  on  posterior  slope,  where  between  some  ribs  are  interspaces  as  wide 
as  the  ribs;  concentric  sculpture  consisting  of  regular,  closely  spaced  con¬ 
centric  threads,  overriding  the  radials,  producing  a  reticulate  sculpture  and 
beading  the  ribs  on  the  posterior  slope;  cardinal  area  narrow,  part  behind 
umbo  depressed,  having  wide  ligament-grooves;  part  under  and  in  front  of 
umbo  wider,  elevated,  and  horizontally  striate;  hinge  as  in  0.  dentera,  but 
5  teeth  are  in  anterior  series  and  18  in  posterior. 

Length  13  mm.;  umbonal  height  7.6  mm.;  maximum  height  8.2  mm.; 
diameter  (right  valve)  2.8  mm.;  length  of  hinge  7  mm. 


40 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


This  species,  also  known  only  from  the  holotype,  closely  resembles 
B.  dentera,  but  is  more  compressed,  and  has  stronger  sculpture. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352750). 

Barbatia  (Obliquarca)  modiolida,  new  species. 

(Plate  3,  Figures  23,  24.) 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  modioliform,  somewhat  compressed,  very  inequilateral, 
posterior  end  higher;  umbos  low,  almost  terminal;  posterior  ridge  not  well 
defined  near  lower  margin,  high  and  broad  in  umbonal  region;  radial 
sculpture  consisting  of  low,  fine  ribs,  separated  by  grooves  in  the  part  in 
front  of  the  posterior  ridge;  radials  behind  posterior  ridge  coarser,  swollen, 
and  separated  by  wider  interspaces;  concentric  sculpture  consisting  of 
threads  and  irregular  incrementals,  producing  a  reticulate  sculpture  on 
unworn  parts  of  shell;  cardinal  area  very  narrow,  part  behind  umbo  deeply 
depressed,  almost  internal,  bearing  2  wide  ligament-grooves;  the  part  under 
umbo  elevated;  anterior  teeth  4  to  6,  slightly  oblique,  more  or  less  irregular, 
subumbonal  in  position,  medial  teeth  very  short  and  weak,  or  absent,  pro¬ 
ducing  a  long  edentulous  gap ;  about  8  oblique  teeth  at  outer  end  of  posterior 
series;  ventral  margin  of  valve  smooth  or  finely  fluted. 

Length  10  mm. ;  umbonal  height  4.1  mm. ;  maximum  height  6  mm. ;  diam¬ 
eter  (left  valve)  1.9  mm. 

The  peculiar  outline  of  this  small  species  at  once  distinguishes  it 
from  the  other  Bowden  Areas.  It  is  represented  by  a  number  of 
valves,  several  of  which  are  slightly  larger  than  the  holotype.  The 
cardinal  area  is  very  narrow  and  the  part  behind  the  umbo  is  so 
deeply  depressed  that  it  is  almost  internal.  The  hinge  is  typical  of 
the  subgenus,  as  it  is  divided  into  two  series,  but  the  teeth  in  the 
middle  of  the  hinge  are  very  weak  or  absent,  leaving  only  the  irregular 
anterior  teeth  and  the  oblique  regular  teeth  at  the  outer  end  of  the 
posterior  series. 

All  the  valves  are  more  or  less  worn,  so  that  their  sculpture  is 
faint.  Several  shells  are  less  inflated  and  more  compressed  in  the 
posterior  dorsal  part  than  the  holotype. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352751). 

Subgenus  DILUVARCA,  new  name. 

Section  DILUVARCA  s.  s. 

Anadara  of  authors,  not  of  Gray,  1847. 

Scapharca  of  authors,  not  of  Gray,  1847. 

Type. — Area  diluvii  Lamarck.  Miocene  to  Recent,  Mediterranean 
Sea. 

The  following  is  a  description  of  the  section  Diluvarca  s.  s. 

Shell  heavy,  medium-sized,  moderately  elongate,  strongly  inflated,  inequi¬ 
lateral,  equivalve,  valves  closed  along  ventral  margin;  umbos  high  and 
full;  sculpture  consisting  of  strong,  narrow,  flattened  radial  ribs  separated 
by  squarely  channeled  interspaces,  ribs  beaded  by  concentric  threads; 


PELECYPODS. 


41 


cardinal  area  relatively  wide,  on  adult  shells  almost  entire  area  occupied 
by  ligament  and  bearing  chevron-shaped  ligament  grooves  diverging  from 
under  umbo  at  an  obtuse  angle;  hinge  uninterrupted,  but  consisting  of  two 
series  of  teeth  unequal  in  length;  the  shorter  anterior  series  comprising 
teeth  that  are  slightly  oblique  at  anterior  end  and  become  vertical  but  not 
much  reduced  in  size  at  posterior  end;  the  longer  posterior  series  comprising 
teeth  that  are  strongly  oblique  at  posterior  end  and  become  vertical  and 
very  small  at  anterior  end;  posterior  muscle-scar  quadrangular,  larger  than 
the  rounded  anterior  scar;  margin  of  valve  deeply  fluted. 

This  group  of  Areas  is  called  Anadara  by  European  paleontologists. 
Gray1  designated  “A.  antiquata,  Area,  sp.  Linn.”  as  the  type  of 
Anadara.  Therefore  the  type  is  Area  antiquata  Linne,  1758,  and  not 
Area  antiquata  Poli  1795  (=. Area  diluvii  Lamarck),  which  usually  is 
given  as  the  type.  The  exterior  of  the  type  of  Area  antiquata  Linne 
has  been  figured  by  Hanley,2  who  states  that  its  locality  is  not  known. 
Figures  1  and  2  on  plate  4  are  photographs  of  Linne's  type  kindly 
sent  by  the  General  Secretary  of  the  Linnean  Society  of  London  and 
published  with  his  consent.  The  number  144  visible  on  figure  1  corre¬ 
sponds  to  the  number  for  Area  antiquata  on  page  694  of  the  tenth 
edition  of  the  Systema  Naturae.  These  photographs  and  Hanley's 
figure  show  that  Area  antiquata  externally  resembles  some  of  the 
American  species  of  Argina,  but  has  a  byssal  gape.  Its  cardinal  area 
is  moderately  wide,  but  no  ligament  grooves  are  visible.  The  hinge 
is  heavy;  the  anterior  series  of  teeth  is  relatively  long  and  not 
clearly  separated  from  the  posterior  series.  There  are  no  similar 
Tertiary  or  living  American  Areas. 

The  same  group  of  Areas  is  called  Scapharca  by  American  paleon¬ 
tologists.  The  type  of  Scapharca  Gray,3  Area  inaequivalvis  Brugiere, 
is  thin-shelled,  subquadrate,  subequilateral,  and  inequivalve,  the  left 
valve  being  larger  than  the  right.  The  cardinal  area  is  very  narrow, 
except  in  front  of  the  umbo,  where  the  ligament  extends  as  a  narrow 
wedge  half  or  less  of  the  distance  from  the  umbo  to  the  anterior 
margin;  the  remainder  of  the  cardinal  area  in  front  of  the  umbo  is 
elevated  and  striate.  The  sculpture  is  similar  to  that  of  Diluvarca. 

Diluvarca  has  essentially  the  same  kind  of  cardinal  area  and  hinge 
as  Barhatia  s.  s.,  but  its  cardinal  area  is  wider;  the  anterior  series  of 
teeth  is  relatively  longer  and  is  not  so  distinctly  separated  from  the 
posterior  series.  On  young  shells  or  on  small  adult  shells  the  ligament 
is  confined  to  the  part  of  the  cardinal  area  behind  the  umbo  and 
contains  one  or  two  oblique  ligament-grooves,  like  in  young  valves 
of  Barhatia  harbata.  On  such  shells  the  part  of  the  cardinal  area  in 
front  of  the  umbo  is  more  elevated  and  has  vertical  and  horizontal 
striations. 

1  J.  E.  Gray.  Proc.  Zool.  Soc.  London,  part  15,  p.  198.  1847. 

2  S.  Hanley.  Ispa  Linnaei  Conchylia,  pp.  93-95,  plate  4,  fig.  3.  1855. 

3  J.  E.  Gray.  Proc.  Zool.  Soc.  London,  part  15,  p.  198.  1847.  Type  (by  original  designa¬ 

tion),  Area  inaequivalvis  Brugui&re. 


42 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


There  are  more  living  and  Tertiary  species  of  Diluvarca  than  of  any 
other  kind  of  Area.  Their  Tertiary  and  present  distribution  is  virtually 
cosmopolitan. 

Key  to  the  Bowden  species  of  Diluvarca  s.  s. 

1.  Outline  not  subglobose. 

A.  Length  of  adult  shell  exceeding  45  mm.,  ribs  num¬ 


bering  35 .  B.  ( D )  halidonata 

B.  Shell  high .  B.  ( D .)  halidonata  halidonata 

BB.  Shell  elongate .  B.  ( D .)  halidonata  oresta 


AA.  Length  of  adult  shell  not  exceeding  45  mm.,  but 
exceeding  10  mm. 

C.  Shell  high. 

D.  Shell  not  obliquely  truncate  pos¬ 

teriorly,  ribs  numbering  33 ..  .  B.  ( D .)  perplura 
DD.  Shell  obliquely  truncate  posteri¬ 
orly,  ribs  numbering  32 .  B.  ( D .)  prephina 

CC.  Shell  elongate. 

E.  Shell  obliquely  extended  poster¬ 

ior^,  ribs  numbering  30 .  B.  ( D .)  inaequilateralis 

EE.  Shell  not  obliquely  extended  pos¬ 
teriorly. 

F.  Ribs  distant. 

G.  Interspaces  wider 

than  ribs,  ribs 
numbering  26. .  B.  (D.)  dasia 
GG.  Interspaces  nar¬ 
rower  than  ribs, 
ribs  numbering 

32 .  B.(D.)  wordeni 

FF.  Ribs  crowded. 

H.  Shell  obliquely 

truncate  pos¬ 
teriorly,  ribs 

numbering  40.  .  B.  ( D .)  agnastha 
HH.  Shell  not  oblique¬ 
ly  truncate  pos¬ 
teriorly,  ribs 

numbering  36 ...  .  B.  (D.)  thomasensis 
AAA.  Length  of  adult  shell  not  exceeding  10  mm.,  ribs 


numbering  24 .  B.(D.)  donacia 

2.  Outline  subglobose. 

I.  Outline  not  cardioid,  shell  moderately  inflated . B.  (D.)  microtera 

II.  Outline  cardioid,  shell  strongly  inflated .  B.  (Z>.)  ophthanta 


Barbatia  (Diluvarca)  halidonata  halidonata  (Dali). 

(Plate  4,  Figures  3,  4.) 

Area  consobrina  Guppy  (not  Sowerby),  1866,  Quart.  Jour.  Geol.  Soc.  London, 
vol.  22,  p.  293.  Guppy  (part,  not  Sowerby),  1874,  Geol.  Mag.,  decade  2, 
vol.  1,  p.  443  (list). 

Scapharca  ( Scapharca )  halidonta  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci., 
Philadelphia,  vol.  3,  part  4,  pp.  646-647,  plate  33,  fig.  24.  Sheldon,  1916, 
Paleontographica  Americana,  vol.  1,  p.  49,  plate  11,  fig.  8. 

The  following  is  the  original  description  of  this  subspecies: 

Shell  subequivalve,  ovate,  oblique,  inflated;  beaks  rather  high,  strongly 
bent  forward,  almost  reaching  the  anterior  fourth  of  the  length;  left  valve 
larger,  with  about  34  clear-cut,  elegantly  sculptured  radial  ribs;  the  anterior 


PELECYPODS. 


43 


dozen  ribs  are  usually  dichotomous  or  deeply  sulcate ;  the  ribs  on  the  middle 
of  the  shell  are  grooved  with  1  or  2  shallow,  sharp,  incised  lines;  the  more 
posterior  ribs  are  wider  and  flatter  with  3  or  more  grooves;  those  on  the 
posterior  dorsal  slope  are  angular,  narrower,  and  usually  have  not  more 
than  1  groove,  which  is  nearly  obsolete;  the  concentric  sculpture  is  of 
evenly  spaced,  fine  elevated  lines  arched  in  the  interspaces  and  finely 
nodulating  the  anterior  ribs;  the  sculpture  is  similar  on  both  valves;  the 
anterior  end  of  the  shell  is  rounded,  the  base  arcuate,  the  posterior  end 
oblique  above  and  produced  below;  the  ends  of  the  hinge-line  are  angulate; 
the  cardinal  area  is  moderately  wide  with  about  3  concentric  lozenges  out¬ 
lined  by  the  grooving;  the  hinge-line  is  straight,  the  teeth  numerous  and 
mostly  vertical,  the  two  series  not  interrupted,  the  posterior  distal  teeth 
tending  to  become  irregular  in  the  adult.  Long,  of  shell  55^01  hinge-line  41, 
alt.  40,  diam.  40  mm. ;  large  specimens  reach  a  length  of  68  mm. 

Type  locality . — Bowden,  Jamaica. 

This  subspecies  is  the  most  abundant  Area  and  all  stages  of  growth 
are  represented.  Young  shells  have  a  different  shape,  as  the  upper  part 
of  the  posterior  lateral  margin  is  not  obliquely  truncated  and  its  lower 
part  is  less  extended.  Young  and  adult  shells  differ  also  in  details  of 
sculpture.  On  medium-sized  shells  only  a  few  of  the  anterior  ribs 
are  grooved  and  the  threads  on  the  posterior  ribs  are  absent ;  on  young 
shells  the  ribs  in  even  the  extreme  anterior  part  of  the  shell  are  not 
grooved;  thus  there  is  a  progressive  decrease  in  the  number  of 
anterior  ribs  that  are  grooved.  Some  immature  shells,  left  valves  in 
particular,  are  more  inflated  than  others  and  have  more  deeply 
channeled  interspaces. 

Guppy  identified  this  species  as  Area  consobrina  Sowerby  (not  A. 
consobrina  d’Orbigny),  described  from  the  Dominican  Republic.  The 
difference  between  the  Bowden  and  Dominican  species  is  described 
under  the  following  subspecies. 

Other  localities. — Miocene,  Curasao.1 

Type  material. — 14  cotypes  (U.  S.  Nat.  Mus.  No.  135756). 

Barbatia  (Diluvarca)  halidonata  oresta,  new  subspecies. 

(Plate  4,  Figures  5,  6.) 

The  following  is  a  description  of  this  subspecies: 

Shell  large,  subtrapezoidal,  elongate,  length  more  than  one  and  one-half 
times  height,  strongly  inflated;  umbo  low  and  flat,  lying  at  almost  anterior 
third  of  shell;  anterior  lateral  margin  rounded;  posterior  lateral  margin 
obliquely  truncated  above  and  extended  below;  posterior  half  of  ventral 
margin  subparallel  to  dorsal  margin,  anterior  half  arcuate;  sculpture  as  in 
B.  halidonata  halidonata. 

Length  70  mm.;  height  44  mm.;  diameter  (right  valve)  21  mm.;  length  of 
hinge  52  mm. 

B.  halidonata  halidonata  is  relatively  high  and  has  high  prominent 
umbos,  but  some  of  the  shells  are  more  elongate  and  have  lower 
umbos.  Three  very  elongate  shells  are  separated  as  the  subspecies 
oresta. 


1  See  footnote  on  page  25. 


44 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


B.  halidonata  oresta  closely  resembles  B.  henekeni  (Maury),  de¬ 
scribed  from  the  Dominican  Republic,  but  is  larger  and  has  less 
deeply  grooved  ribs.  The  Bowden  subspecies  also  resembles  B.  lienosa 
(Say),  from  the  upper  Miocene  (Duplin  marl)  and  Pliocene  (Wacca- 
maw  and  Caloosahatchee  marls),  but  is  smaller,  less  evenly  rounded 
anteriorly,  and  has  fewer  and  higher  ribs.  The  living  West  Indian 
species,  B.  secticostata  (Reeve)  is  more  evenly  rounded  anteriorly  and 
has  wider  interspaces. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352752). 

Barbatia  (Diluvarca)  perplura,  new  species. 

(Plate  4,  Figure  7.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  heavy,  greatly  inflated,  moderately  inequilateral; 
base  gently  and  evenly  rounded ;  anterior  and  posterior  ends  rounded ;  umbos 
moderately  high,  bearing  an  inconspicuous  median  groove,  lying  at  about 
anterior  third  of  length;  radial  sculpture  consisting  of  33  flat-topped  ribs 
of  uniform  width,  separated  by  narrower  deeply  channeled  interspaces;  on 
the  posterior  slope  the  ribs  are  lower  and  the  interspaces  wider  than  in  other 
parts  of  shell;  concentric  sculpture  consisting  of  fine,  usually  evenly  spaced 
threads,  producing  low  beads  on  the  ribs,  except  on  posterior  slope;  cardinal 
area  moderately  wide,  bearing  2  ligament-grooves  behind  umbo;  margin  of 
valve  deeply  fluted. 

Length  23.5  mm.;  height  17.5  mm.;  diameter  (left  valve)  9.6  mm.;  length 
of  hinge  17  mm. 

B.  perplura  is  represented  by  2  left  valves.  It  closely  resembles 
small  shells  of  B.  halidonata,  but  is  more  elongate,  heavier,  less  com¬ 
pressed  in  the  posterior  dorsal  part,  more  inflated,  and  has  fuller, 
more  prominent  umbos,  higher  ribs,  and  more  deeply  channeled  inter¬ 
spaces.  It  is  smaller  than  B.  actinophora  (Dali),  from  the  Gatun 
formation  of  the  Canal  Zone,  and  has  fewer  and  wider  ribs. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352753). 

Barbatia  (Diluvarca)  prephina,  new  species. 

(Plate  4,  Figure  8.) 

.Area  ( Scapharca )  auriculata  Lamarck  ?,  Dali,  1898,  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  p.  649. 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  greatly  inflated;  posterior  end  truncated;  anterior 
end  rounding  by  a  broad  curve  into  the  gently  and  asymmetrically  arcuate 
base;  umbos  moderately  high,  lying  at  about  anterior  third  of  length; 
posterior  ridge  strong,  rounded,  posterior  slope  excavated;  left  valve  slightly 
larger,  sculptured  with  32  square  ribs  separated  by  interspaces  wider  than 
the  ribs  in  anterior  and  middle  parts  of  shell,  but  narrower  in  posterior  part; 
on  anterior  half  of  shell  lower  parts  of  ribs  grooved,  on  the  posterior  slope 
they  are  flatter  and  broader;  all  ribs  except  those  on  the  posterior  slope 
beaded  by  numerous  concentric  threads  extending  across  interspaces;  right 


PELECYPODS. 


45 


valve  sculptured  with  30  lower  and  broader  ribs,  interspaces  of  about  the 
same  width  in  anterior  half  of  shell  and  narrower  in  posterior  half;  only  the 
anterior  6  or  7  ribs  grooved;  beads  limited  to  the  anterior  ribs  and  not  so 
sharp  as  on  left  valve;  cardinal  area  moderately  wide,  bearing  3  to  5  liga¬ 
ment  grooves  behind  umbo. 

A  right  valve  (holotype) :  length  35  mm.;  height  24  mm.;  diameter  10 
mm.;  length  of  hinge  22  mm.  A  left  valve:  length  38  mm.;  height  25  mm.; 
diameter  12.5  mm.;  length  of  hinge  24  mm. 

B.  prephina  closely  resembles  the  living  West  Indian  B.  auriculata 
(Lamarck).  The  Bowden  species  is  smaller,  has  more  numerous, 
lower,  and  more  conspicuously  headed  ribs,  and  much  narrower  inter¬ 
spaces.  Maury  records  B.  auriculata  from  Miocene  beds  in  the 
Dominican  Republic,  and  Olsson  from  Miocene  beds  in  Costa  Rica. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352754). 


Barbatia  (Diluvarca)  inaequilateralis  (Guppy). 

(Plate  5,  Figures  1  to  3.) 

Area  inaequilateralis  Guppy,  1866,  Quart.  Jour.  Geol.  Soc.  London,  vol.  22, 
pp.  293-294,  plate  28,  fig.  2.  Guppy,  1874,  Geol.  Mag.,  decade  2,  vol.  1, 
p.  443  (list).  Sheldon,  1916,  Paleontographica  Americana,  vol.  1,  p.  50, 
plate  11,  figs.  11,  12.  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.  Philadelphia, 
vol.  73,  p.  403. 

Scapharca  ( Scapharca )  inaequilateralis  (Guppy),  Dali,  1898,  Trans.  Wagner 
Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  p.  647. 

Scapharca  inaequilateralis  (Guppy)  Maury,  1917,  Bull.  Amer.  Paleontology, 
vol.  5,  p.  335,  plate  56,  fig.  8. 

The  following  is  the  original  description  of  this  species: 

Shell  transverse,  slightly  oblique,  very  inequilateral,  produced  posteriorly; 
valves  with  about  30  crenate  radiating  ribs,  single  on  the  disk,  where  they 
are  not  broader  than  one-third  of  their  interstices;  double  anteriorly  and 
posteriorly,  where  they  are  equal  in  width  to  the  interstices;  hinge-line  long, 
straight,  forming  an  abrupt  angle  with  the  rounded  anterior  margin;  pos¬ 
terior  margin  with  an  oblique  slope. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  thin,  elongate,  subovate,  moderately  inflated;  umbos  low, 
lying  at  about  anterior  third  of  length;  upper  part  of  posterior  margin 
obliquely  truncated,  lower  part  extended;  ventral  margin  sloping  toward 
posterior  end;  sculpture  of  the  two  valves  similar,  consisting  of  about  30 
radial  ribs,  the  one  adjacent  to  the  anterior  dorsal  margin  usually  small 
and  narrow;  the  next  8  to  12  broad,  wider  than  the  interspaces  which  bear 
a  shallow,  broad,  median  groove;  ribs  in  central  part  of  shell  narrow,  usually 
less  than  half  as  wide  as  interspaces,  and  usually  square;  posterior  ribs, 
9  to  11  in  number,  much  wider  than  interspaces,  flat,  and  bearing  a  narrow 
groove  (rarely  2),  which  almost  or  entirely  disappears  on  the  ribs  in  extreme 
posterior  dorsal  part;  concentric  sculpture  consisting  of  fine,  closely  set 
threads,  producing  on  the  grooved  anterior  ribs  a  double  row  of  beads  and 
a  single  row  on  the  undivided  medial  ribs,  the  beads  of  the  median  ribs 


46 


MTOCENE  MOLLUSKS  FROM  BOWDEN. 


usually  more  conspicuous  on  the  left  valve;  posterior  ribs  not  affected  by 
the  concentric  sculpture;  cardinal  area  narrow,  bearing  1  to  3  ligament 
grooves  behind  the  umbo;  ventral  margin  of  valve  deeply  fluted  and  from 
the  flutings  faint  rays,  most  noticeable  in  the  posterior  part,  run  up  toward 
the  umbo. 

Length  31  mm.;  height  16.7  mm.;  diameter  (right  valve)  7  mm.;  length 
of  hinge  19  mm. 

The  small  thin  shells  of  this  species  are  numerous.  A  few  shells 
have  a  faint  shallow  groove  on  the  umbo. 

B.  inaequilateralis  closely  resembles,  as  Dali  has  pointed  out,  B. 
latidentata  (Dali)  described  from  the  Chipola  formation,  but  its 
posterior  end  is  more  extended,  and  it  has  a  thinner  shell,  narrower 
ribs,  and  finer,  shorter,  and  more  numerous  teeth.  Maury  has 
recorded  B.  inaequilateralis  from  the  Cercado  formation  of  the 
Dominican  Republic. 

Other  localities . — Cercado  formation  (lower  Miocene),  Dominican 
Republic. 

Type  material. — 2  cotypes  (British  Museum  (Natural  History), 
Geological  Department,  No.  64089). 

Barbatia  (Diluvarca)  dasia,  new  species. 

(Plate  5,  Figure  4.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  heavy,  subrhomboidal,  elongate,  much  inflated,  pos¬ 
terior  end  slightly  higher  and  obliquely  truncate;  umbo  high,  inflated,  the 
tip  slightly  depressed  medially;  left  valve  sculptured  with  26  high,  square 
ribs,  separated  by  wider  deeply  channeled  interspaces;  on  the  posterior 
slope  the  ribs  are  lower  and  flatter;  anterior  ribs  about  as  wide  as  inter¬ 
spaces;  concentric  sculpture  consisting  of  threads,  producing  faint  beads  on 
tops  of  ribs  and  inconspicuous  threads  on  sides  of  ribs  and  in  interspaces; 
cardinal  area  moderately  wide,  wider  in  front  of  umbo,  bearing  5  ligament 
grooves  behind  umbo ;  ventral  margin  of  valve  bearing  broad,  deep  flutings. 

Length  31.5  mm.;  height  19  mm.;  diameter  (left  valve)  10  mm.;  length 
of  hinge  23  mm. 

This  species,  which  is  represented  only  by  the  holotype,  a  left  valve, 
closely  resembles  B.  honensis  (Olsson),1  a  Miocene  species  from  Costa 
Rica,  but  is  lower  and  its  anterior  end  is  more  extended. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352755). 

Barbatia  (Diluvarca)  wordeni,  new  species. 

(Plate  5,  Figure  5.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  moderately  inflated,  heavy,  elongate;  umbo  inflated, 
low,  bearing  a  faint  median  groove;  left  valve  sculptured  with  32  square, 
ribs  of  almost  uniform  wridth  except  at  ends,  flattened  on  the  posterior 
slope;  interspaces  narrower  than  ribs;  except  on  the  posterior  slope  the  ribs 


1  Comparison  based  on  figures. 


PELECYPODS. 


47 


and  interspaces  are  crossed  by  concentric  threads  beading  the  ribs;  right 
valve  sculptured  with  30  or  31  lower  and  usually  narrower  ribs,  separated 
by  interspaces  of  about  the  same  width;  concentric  threads  prominent  in 
interspaces,  but  beading  only  a  few  anterior  ribs;  cardinal  area  narrow, 
bearing  1  or  2  ligament  grooves  behind  umbo ;  ventral  margin  deeply  fluted. 

Length  25.5  mm.;  height  17  mm.;  diameter  (left  valve)  8.2  mm.;  length 
of  hinge  18  mm. 

B.  wordeni  is  characterized  by  its  rather  elongate  and  inflated  out¬ 
line,  thick  shell,  and  relatively  high  undivided  ribs  separated  by 
deeply  channeled  interspaces.  Young  shells  are  proportionately  less 
inflated  than  adults  and  their  umbonal  groove  is  more  prominent. 
B.  inaequilateralis  is  of  about  the  same  size,  but  is  much  thinner,  more 
extended  at  the  posterior  end,  less  inflated,  and  has  finer  ribs;  B. 
perplura  is  higher,  heavier,  and  has  fuller,  more  prominent  beaks, 
wider  ribs,  and  narrower  interspaces.  B.  hypomela  (Dali),  described 
from  the  Chipola  formation,  has  the  same  outline,  but  is  much  larger 
and  has  lower,  deeply  grooved  ribs  and  wider  cardinal  area. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352756). 

Barbatia  (Diluvarca)  agnastha,  new  species. 

(Plate  5,  Figure  6.) 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  moderately  inflated,  posterior  end  higher,  posterior  dorsal 
part  compressed,  posterior  margin  truncated;  umbo  low,  relatively  broad, 
placed  at  about  anterior  third  of  length,  bearing  an  obscure  median  groove; 
sculpture  consisting  of  40  low,  narrow,  flat  radial  ribs,  broader  and  flatter 
on  the  posterior  slope,  separated  by  narrower  interspaces ;  in  the  interspaces 
are  faint  concentric  threads  that  extend  across  the  ribs,  except  those  on  the 
posterior  slope,  producing  obscure  beads;  cardinal  area  moderately  wide, 
bearing  a  ligament-groove  behind  umbo;  ventral  margin  fluted. 

Length  21.8  mm.;  height  12.8  mm.;  diameter  (right  valve)  5  mm.;  length 
of  hinge  16  mm. 

The  posterior  dorsal  compression  produces  an  auriculate  outline, 
particularly  on  small  shells.  The  ventral  margin  rapidly  ascends 
toward  the  anterior  end.  These  features,  the  numerous  narrow,  flat¬ 
tened  ribs  and  small  size  of  the  shell  separate  this  species  from  the 
other  Diluvarcas.  Small  shells,  besides  being  more  auriculate,  have  a 
relatively  higher  posterior  end  and  more  prominent  umbonal  groove. 
It  is  difficult  to  separate  young  shells  of  B.  agnastha  and  of  B. 
wordeni;  those  of  B.  agnastha  usually  are  more  elongate,  more  auri¬ 
culate  and  have  more  numerous  and  finer  ribs.  The  adults  are  easily 
separated,  as  the  shell  of  B.  wordeni  is  heavier,  larger,  higher,  more 
inflated,  and  its  ribs  are  coarser  and  higher.  B.  agnastha  is  smaller, 
thinner,  more  elongate,  and  less  inflated  than  B.  prephaina  and  has 
more  numerous  and  finer  ribs.  B.  acompsa  (Dali),  described  from 
the  Chipola  formation,  has  a  more  extended  anterior  margin,  a 
straighter  base,  wider  and  divided  ribs. 


48 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Type  material . — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352757). 

Barbatia  (Diluvarca)  thomasensis,  new  species. 

(Plate  5,  Figure  7.) 

The  following  is  a  description  of  this  species: 

Shell  small,  inflated,  moderately  inequilateral,  posterior  end  slightly 
extended;  umbo  moderately  high,  lying  in  front  of  middle,  the  tip  slightly 
grooved  medially;  sculpture  consisting  of  36  narrow,  square-topped  closely 
set  radial  ribs,  separated  by  narrower  interspaces;  the  anterior  7  or  8 
ribs  and  the  accompanying  interspaces  relatively  wide;  the  next  8  narrow 
and  the  following  ones  progressively  slightly  broader,  those  on  the  posterior 
slope  broadest  and  flattest;  concentric  sculpture  consisting  of  irregular 
inconspicuous  threads  that  faintly  and  unevenly  bead  the  anterior  and 
median  ribs;  cardinal  area  moderately  wide,  bearing  a  single  ligament 
groove  behind  the  umbo;  ventral  margin  of  shell  deeply  fluted;  interior  of 
shell  marked  with  fine  inconspicuous  radial  rays. 

Length  19.5  mm.;  height  12  mm.;  diameter  (left  valve)  5.1  mm.;  length 
of  hinge  14  mm. 

This  species  is  represented  by  a  left  valve.  It  may  be  a  young 
shell  similar  to  B.  actinophora  (Dali),  from  the  Gatun  formation  of 
the  Canal  Zone,  but  no  larger  shells  have  been  found.  In  outline  and 
in  the  number  and  size  of  the  ribs  it  resembles  the  much  larger  Gatun 
species.  It  also  is  very  similar  to  B.  willobiana  (Cooke),  a  middle 
Oligocene  species  of  the  same  size  from  Antigua,  but  is  more  inflated 
and  has  a  few  more  ribs. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352758). 

Barbatia  (Diluvarca)  donacia  (Dali). 

(Plate  5,  Figures  8  to  11.) 

Scapharca  ( Scapharca )  donacia  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  4,  p.  649,  plate  33,  fig.  13.  Sheldon,  1916, 
Paleontographica  Americana,  vol.  1,  p.  50,  plate  11,  fig.  14. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  donaciform,  moderately  plump,  with  rather  elevated  proso- 
coelous  beaks  at  about  the  anterior  third;  valves  almost  similarly  sculp¬ 
tured;  left  valve  with  about  24  low,  strap-like,  narrow  radial  ribs  with 
somewhat  wider  interspaces;  the  ribs  are  plain,  smooth,  and  entire  on  both 
valves ;  on  the  left  valve  the  interspaces  are  crossed  by  numerous  equidistant 
elevated  lines  which  do  not  appear  on  the  ribs;  on  the  right  valve  the 
interspaces  are  only  marked  by  lines  of  growth;  hinge-line  short,  cardinal 
area  very  narrow,  smooth ;  anterior  end  larger,  rounded ;  posterior  end  pro¬ 
duced  and  attenuated;  hinge  teeth  small,  similar,  slightly  divergent;  internal 
margin  of  the  valves  with  deep  short  flutings.  Lon.  6.8,  alt.  4.5,  diam.  3  mm. 

Type  locality — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

The  umbos  are  relatively  high  and  conspicuous.  The  umbo  of  most  right 
valves  bears  a  shallow  narrow  groove.  Toward  the  ventral  margin  this 


PELECYPODS. 


49 


groove  broadens  and  slightly  emarginates  the  base.  On  the  left  valve  the 
groove  is  absent  or  obscure.  The  ribs  (4  to  6)  in  the  groove,  and  in  a  cor¬ 
responding  position  on  left  valves,  are  narrower  and  flatter  than  the  others. 
On  unworn  valves  fine,  evenly  and  closely  spaced  concentric  threads,  usually 
more  prominent  on  left  valves,  are  visible  in  the  interspaces.  The  cardinal 
area  is  narrow  and  bears  a  single  ligament  groove  behind  the  umbo.  The 
deep,  short  flutings  of  the  ventral  margin  are  absent  where  the  median 
groove  reaches  the  base. 

Length  9  mm.;  height  6  mm.;  diameter  (right  valve)  2.5  mm.;  length 
of  hinge  5  mm. 

B.  donacia  is  a  small  species,  but  is  represented  by  a  large  number 
of  shells  of  various  stages  of  growth.  B.  cibaoica  (Maury),  a  very 
similar  species  described  from  the  Cercado  formation  of  the  Domin¬ 
ican  Republic  and  also  known  in  the  Gurabo  formation,  is  less 
elongate  and  has  a  more  conspicuous  median  groove.  A  similar  small 
Diluvarca,  B.  guajataca  (Maury  and  Sheldon),1  has  been  described 
from  the  lower  Miocene  Quebradillas  limestone  of  Porto  Rico.  It  is 
less  elongate  than  B.  donacia  and  has  more  ribs. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  61628). 

Barbatia  (Diluvarca)  microtera,  new  species. 

(Plate  5,  Figures  12,  13.) 

Scapharca  ( Argina )  tolepia  Dali  (part),  1898,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  4,  pp.  649-650,  not  plate  33,  figs.  7,  8. 

¥ 

The  following  is  a  description  of  this  species: 

Shell  small,  inflated,  greatest  inflation  and  greatest  height  of  shell  behind 
middle;  right  valve  smaller,  more  rounded,  its  posterior  end  lower  than  in 
left;  umbos  full,  broad,  medially  grooved,  lying  at  about  anterior  third  of 
length ;  left  valve  sculptured  with  36  to  38  strong  ribs ;  anterior  and  median 
ribs  subrounded,  separated  by  narrower  interspaces,  and  bearing  beads  con¬ 
nected  across  interspaces  by  threads ;  posterior  ribs  lower,  flatter,  separated 
by  interspaces  of  almost  the  same  width,  smooth  or  inconspicuously  beaded; 
right  valve  sculptured  with  28  to  30  obscurely  beaded  ribs  separated  by 
deeply  channeled  interspaces  of  the  same  width  or  slightly  wider;  cardinal 
area  very  narrow;  hinge  consisting  of  two  sets  of  teeth  which  are  not  inter¬ 
rupted,  the  shorter  anterior  series  comprising  vertical  and  slightly  oblique 
teeth,  the  longer  posterior  series  consisting  of  more  oblique  teeth;  margin 
of  valve  deeply  fluted. 

Length  6.1  mm.;  height  5.9  mm.;  diameter  (left  valve)  1.8  mm.;  length 
of  hinge  4  mm. 

This  species  closely  resembles  very  young  shells  of  the  Dominican 
species  B.  tolepia  (Dali),  but  is  more  rounded  and  has  more  numerous 
ribs. 

The  type  of  Area  tolepia  Dali  (U.  S.  Nat.  Mus.  No.  113801)  has 
the  locality  label  “Potrero,  Rio  Amina,  St.  Domingo.”  The  locality 
given  for  the  published  figure  in  the  explanation  of  the  plate, 
“Bowden,  Jamaica,”  is  incorrect.  Area  tolepia  is  the  species  to  which 


1  Comparison  based  on  figures. 


50 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Maury  later  gave  the  name  Scapharca  arthurpennelli.  It  has  the 
cardinal  area  and  hinge  of  small  species  of  Diluvarca,  but  the  shape 
suggests  the  group  Argina  Gray.  This  species  is  confined  to  the 
Cercado  formation  according  to  the  collections  of  both  the  Maury 
and  U.  S.  Geological  Survey  parties. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352760). 

Barbatia  (Diluvarca)  opthanta,  new  species. 

(Plate  5,  Figs.  14,  15.) 

The  following  is  a  description  of  this  species: 

Shell  small,  cardioid,  height  exceeding  length,  decidedly  inflated,  posterior 
end  higher,  moderately  inequilateral;  left  valve  larger  and  more  inflated 
than  right,  and  having  higher  umbo;  dorsal  margins  short;  base  descending 
toward  posterior  end;  umbos  high,  full,  subcentral;  sculpture  consisting  of 
26  to  28  ribs,  conspicuously  beaded  on  left  valve  except  on  umbo,  but  the 
right  valve  has  only  a  few  ribs  beaded  at  the  anterior  end;  cardinal  area 
narrow  behind  umbo,  shorter  and  wider  in  front  of  umbo,  part  behind  umbo 
bearing  2  almost  horizontal  ligament  grooves ;  inner  margin  of  valve  deeply 
fluted. 

Length  7.5  mm.;  height  7.8  mm.;  diameter  (left  valve)  3.5  mm.;  length 
of  hinge  4.5  mm. 

This  small  species  is  remarkably  similar  to  very  young  shells  of 
the  Dominican  species  B.  corcupidonis  (Maury),  which  is  confined 
to  the  Cercado  formation  in  the  Dominican  Republic.  The  Bowden 
shells  seem  to  be  full  grown,  as  they  have  a  wider  cardinal  area  and 
heavier  hinge  than  shells  of  the  Dominican  species  of  the  same  size; 
in  addition,  the  umbos  of  the  Bowden  species  are  slightly  narrower 
and  the  number  of  ribs  is  greater. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352761). 

Genus  FOSSULARCA  Cossmann. 

Subgenus  FOSSULARCA  s.  s. 

Cossmann,  1887,  Catalogue  Illustre  des  Coquilles  Fossiles  de  TEocene  des 
Environs  de  Paris,  part  2,  p.  142. 

Type  (by  original  designation). — Area  quadrilatera  Lamarck. 
Eocene,  Paris  Basin. 

The  following  is  a  description  of  the  genus  Fossularca  s.  s.: 

Shell  small,  subquadrate,  moderately  inequilateral;  umbos  high;  sculpture 
consisting  of  fine  radial  ribs  crossed  by  conspicuous  growth-lines;  cardinal 
area  narrow,  bearing  under  umbo  a  small  triangular  ligament  area  marked 
by  vertical  grooves;  remainder  of  cardinal  area  bearing  faint  longitudinal 
striations;  hinge  consisting  of  a  short  series  of  oblique  anterior  teeth  sepa¬ 
rated  by  a  gap  from  a  longer  series  of  oblique  posterior  teeth;  posterior 
muscle-scar  larger  than  anterior,  inner  edge  of  both  muscle-scars  extending 
out  as  a  thin  shelf ;  ventral  margin  of  valve  smooth  or  finely  fluted. 

The  triangular  ligament  area  is  a  characteristic  feature  of  this 
genus.  Cossmann1  has  described  a  separate  section  Galactella  with 


1  In  M.  Cossmann  and  A.  Peyrot.  Conch.  N6og.  de  TAquitaine,  vol.  2,  part  1,  p.  192.  1912. 


PELECYPODS. 


51 


the  living  European  species  Area  lactea  Linne  as  the  type.  The  liga¬ 
ment  area  of  A.  lactea  is  larger  than  in  A.  quadrilatera,  but  the  size 
of  the  ligament  area  seems  to  be  a  variable  feature.  In  the  living 
American  A.  adamsi  Dali  it  is  narrower  than  in  A.  lactea .  The  sepa¬ 
ration  of  the  section  Galactella  seems  unwarranted. 

Stephenson/  who  has  recently  called  attention  to  the  similarity  of 
Fossularca  and  Striarca  Conrad  (type,  Area  centenaria  Say),  regards 
the  two  groups  as  representing  the  same  generic  form.  They  have 
similar  cardinal  areas  and  muscle-scars,  but  Fossularca  has  two  dis¬ 
tinct  series  of  teeth  separated  by  an  edentulous  gap  under  the  narrow 
ligament  area,  and  this  gap  is  not  due  to  the  downward  extension  of 
the  ligament  area.  In  Striarca  the  teeth  are  not  interrupted  and  are 
not  clearly  divided  into  two  series.  This  fundamental  hinge  difference 
combined  with  the  geologic  history  of  the  groups  seems  to  warrant 
the  retention  of  Fossularca  as  a  separate  genus. 

Fossularca  first  appears  in  Eocene  deposits  in  Europe.  It  is  not 
certainly  recorded  in  American  before  lower  Miocene  time.  The  few 
living  species  inhabit  the  warm  and  temperate  seas. 

Fossularca  (Fossularca)  adamsi  sawkinsi,  new  subspecies. 

(Plate  5,  Figs.  16,  17.) 

Barbatia  ( Fossularca )  adamsi  (Shuttleworth)  Smith,  Dali,  (part)  1898,  Trans. 
Wagner  Free  Inst.  Sci.,  Philadelphia,  vol.  3,  part  4,  pp.  629-630. 

Area  adamsi  (Shuttleworth)  Smith,  Sheldon  (part)  1916,  Paleontographica 
Americana,  vol.  1,  p.  22,  not  plate  4,  figs.  16  to  18,  plate  5,  fig.  1. 

The  following  is  a  description  of  this  subspecies: 

Shell  small,  moderately  inflated,  subtrapezoidal,  slightly  inequilateral; 
ventral  margin  slightly  contracted  medially ;  posterior  ridge  low  and  broad ; 
umbos  relatively  low,  broad,  lying  slightly  in  front  of  middle;  sculpture 
consisting  of  “blisters”  more  or  less  connected  radially  and  concentrically, 
forming  a  delicate  cancellate  sculpture ;  beneath  the  blisters,  wrhich  are  par¬ 
tially  or  even  entirely  removed,  are  faint  slightly  elevated  radial  and  con¬ 
centric  threads,  and  irregularly  spaced  growth  lines;  cardinal  area  narrow, 
excavated,  ligament  seated  on  a  narrow  subumbonal  triangular  area;  teeth 
in  two  series  separated  by  a  narrow  subumbonal  edentulous  space ;  about  15 
in  the  posterior  series  and  8  in  the  anterior;  muscular  impressions  bounded 
by  raised  ridges  converging  toward  umbo;  inner  margin  of  valve  usually 
smooth. 

Length  8.5  mm.;  height  5.3  mm.;  diameter  (left  valve)  1.8  mm. 

The  Bowden  shells  closely  resemble  the  living  east  coast  and  West 
Indian  F.  adamsi  adamsi  (Dali),  but  are  smaller  and  have  a  less 
deeply  emarginate  ventral  margin,  narrower  ligament  area  and  corre¬ 
spondingly  narrower  edentulous  gap  in  the  hinge.  F .  adamsi  adainsi 
has  been  reported  from  the  American  mainland  from  beds  ranging 
in  age  from  lower  Miocene  to  Quaternary. 

1  L.  W.  Stephenson.  North  Carolina  Geological  and  Economic  Survey,  vol.  5,  part  1  pp. 
108-110.  1923. 


52 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Recent  specimens  apparently  were  early  distributed  under  the 
manuscript  name  of  A.  adamsi  Shuttleworth,  but  Dali1  was  the  first 
to  publish  the  name  accompanied  by  a  description,  as  Gardner2  has 
shown.  Smith,3  to  whom  the  species  usually  is  assigned,  published  his 
description  two  years  later. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352762). 

Subgenus  OVALARCA,  new  subgenus. 

Type. — Barbatia  ( Fossularcaf )  ovalina  Dali.  Miocene,  Jamaica. 

The  following  is  a  description  of  the  subgenus  Ovalarca: 

Shell  very  small,  ovate,  strongly  inflated,  strongly  inequilateral;  sculpture 
consisting  of  fine  concentric  rugae  and  obscure  distant  radials;  cardinal 
area  very  narrow,  bearing  a  small,  deep  triangular  ligament  area  under 
the  umbo;  hinge  nuculoid,  consisting  of  an  anterior  and  posterior  series,  the 
posterior  series  longer,  the  two  series  separated  by  an  edentulous  subumbonal 
gap;  muscle-scars  high  up  in  shell,  posterior  scar  larger  than  anterior,  inner 
edge  of  both  scars  raised ;  ventral  margin  of  valve  smooth. 

The  subumbonal  triangular  ligament  area  suggests  that  Ovalarca 
is  similar  to  Fossularca  s.  s.,  but  the  cardinal  area  is  narrower  and  all 
other  features  are  different.  According  to  Smith,  the  type  of  Lis- 
sarca ,4  has  more  anterior  umbos,  more  numerous  teeth,  and  a  fluted 
ventral  margin.  Suter5 6  places  Lissarca  in  the  family  Limopsidae. 

The  type  is  the  only  known  Ovalarca. 

Fossularca  (Ovalarca)  ovalina  (Dali). 

(Plate  5,  Figures  18  to  21.) 

Barbatia  ( Fossularca ?)  ovalina,  Dali.  1898,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  4,  p.  630,  plate  32,  fig.  18.  Sheldon,  1916, 
Paleontographica  Americana,  vol.  1,  p.  22,  plate  5,  fig.  2. 

The  following  is  the  original  description  of  this  species: 

Shell  minute,  solid,  ovate,  with  rather  inflated  valves;  beaks  low  in  the 
anterior  fourth,  prosogyrate;  cardinal  area  short,  narrow,  smooth,  or  longi¬ 
tudinally  striate,  the  part  occupied  by  the  ligament  forming  a  small  exca¬ 
vated  triangle  with  the  apex  at  the  beak  in  each  valve;  surface  nearly 
smooth,  sculpture  of  faint,  irregular,  concentric  lines,  crossed  by  still  fainter 
sparse  radiations  which  are  not  pronounced  enough  to  modify  the  surface; 
inner  margin  of  the  valves  smooth;  muscular  impressions  large;  hinge  short 
with  about  3  crowded  anterior  and  4  oblique  posterior  teeth,  the  two  series 
separated  by  a  wide  gap  below  the  ligament.  Lon.  3.2,  alt.  2.5,  diam.  2  mm. 

Type  locality. — Bowden,  Jamaica. 

Two  right  valves  of  this  species  are  in  the  Johns  Hopkins  Univer¬ 
sity  collection,  and  in  the  National  Museum  collection  there  is  a  left 

1  W.  H.  Dali.  Bull.  Mus.  Com.  Zool.  Harvard,  vol.  12,  p.  243.  1886. 

2  J.  A.  Gardner.  MS. 

3  E.  A.  Smith.  Jour.  Linn.  Soc.  London,  Zool.,  vol.  20,  p.  499,  plate  30,  figs.  6,  6a.  1888. 

4  E.  A.  Smith.  Zoology  of  the  Transit  of  Venus  Expedition,  Mollusca,  p.  19,  plate  9,  fig.  17. 

1877.  Type  (by  monotypy). — Area  ( Lissarca )  rubrofusca  Smith.  Recent,  Kerguelen  Island. 

6  H.  Suter.  Man.  New  Zealand  Moll.,  p.  853.  1913. 


PELECYPODS. 


53 


valve  in  addition  to  the  holotype.  The  hinge  has  4  anterior  and  5 
posterior  teeth. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 

135761). 

Genus  BATHYARCA  Kobelt. 

Kobelt,  1891,  Systematisches  Conchylien-Cabinet  von  Martini  und  Chemnitz, 
vol.  8,  part  2 ;  Die  Gattung  Area  L.,  pp.  213-214. 

Type  (by  original  designation). — Area  pectunculoides  Scacchi. 
Recent,  seas  of  Europe. 

The  following  is  a  description  of  the  genus  Bathyarca : 

Shell  minute,  subglobose,  inequivalve,  left  larger  than  right;  sculpture 
consisting  of  fine  radial  and  concentric  threads,  usually  slightly  discrepant 
on  the  two  valves;  cardinal  area  very  narrow,  widening  in  front  of  umbo; 
ligament  grooves  confined  to  a  small  area  at  posterior  end  of  cardinal  area ; 
hinge  consisting  of  two  short  series  of  very  oblique  teeth;  margin  of  valve 
faintly  fluted. 

The  ligament  is  confined  to  a  small  area  back  of  the  umbo  like  in 
small  Barbatias.  The  hinge  is  more  like  that  of  Cucullaria  than  like 
any  of  the  Areas. 

The  living  species  of  Bathyarca  are  confined  to  relatively  deep 
water.  West  Indian  and  Atlantic  coast  American  Tertiary  and  living 
species — except  Bathyarca  spenceri  (Dali),  a  Miocene  species  from 
the  Isthmus  of  Tehuantepec,  Mexico — are  very  small,  like  the  type 
species.  Bathyarca  pompholyx  Dali,  a  living  species  from  off  the 
coast  of  California,  the  Galapagos  Islands,  and  the  mid-Pacific,  is 
relatively  gigantic.  Cossmann  has  suggested  that  Area  lissa  Bayan 
(—A.  laevigata  Caillat),  an  Eocene  species  from  the  Paris  Basin,  is 
an  ancestral  Bathyarca. 

Bathyarca  hendersoni  (Dali). 

(Plate  6,  Figures  1  to  3.) 

Scapharca  ( Bathyarca )  hendersoni  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  4,  p.  653,  plate  33,  fig.  9.  Sheldon,  1916,  Paleon- 
tographica  Americana,  vol.  1,  pp.  63-64,  plate  16,  fig.  1. 

The  following  is  the  original  description  of  this  species: 

Shell  very  small,  much  inflated,  the  hinge-line  as  long  as  the  shell,  which 
is  of  a  rounded  triangular  form,  with  rather  prominent  prosocoelous  beaks; 
left  valve  with  fine,  elevated  rounded  concentric  lines,  crossed  by  closer, 
less  prominent,  and  finer  radial  lines;  in  the  right  valve,  as  usual  in  this 
section  of  the  genus,  the  radial  sculpture  predominates  over  the  concentric, 
the  latter  though  present  being  inconspicuous;  cardinal  area  moderately 
wide,  the  beaks  being  nearly  medial,  the  surface  of  the  area  longitudinally 
striated ;  hinge  with  about  five  nearly  vertical  anterior  teeth  separated  by  a 
wide  unarmed  gap  from  six  or  seven  smaller,  more  oblique  posterior  teeth; 
margin  of  the  valves  thin,  entire,  or  microscopically  crenulated;  the  inner 
edges  of  the  adductor  scars  slightly  raised  above  the  inner  surface  of  the 
valve.  Lon.  2,  alt.  2,  diam.  2  mm. 


54 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Type  locality. — Bowden,  Jamaica. 

In  the  Duerden  collection  there  are  only  a  few  valves  of  this  small 
species,  but  there  is  a  surprisingly  large  number  in  the  Aldrich  collec¬ 
tion.  The  shell  is  much  higher  at  the  posterior  end,  as  the  anterior 
margin  descends  steeply.  The  posterior  margin  is  only  gently  curved. 
The  greatest  inflation  is  in  the  median  posterior  part.  For  the  size 
of  the  shell  the  umbos  are  very  broad;  they  are  placed  slightly  in 
front  of  the  middle.  On  some  shells  a  very  faint  groove  is  visible  on 
the  umbo.  When  continued  the  groove  is  on  the  anterior  side  of  the 
median  line  of  the  shell  and  slightly  insinuates  the  ventral  margin. 
As  usual  in  the  genus,  the  left  valve  is  larger.  The  convexity  of  left 
valves  is  variable.  The  less  convex  shells  have  a  narrower  cardinal 
area  and  more  oblique  anterior  teeth. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135760). 

Family  LIMOPSIDAE. 

Genus  LIMOPSIS  Sassi. 

Subgenus  LIMOPSIS  s.  s. 

Sassi,  1827,  Giornale  ligustico  di  scienze,  letters,  ed  arti,  year  1,  p.  476. 

Type. — Area  aurita  Brocchi.  Miocene  and  Pliocene,  Italy. 

The  following  is  a  description  of  the  subgenus  Limopsis  s.  s.: 

Shell  medium-sized,  obliquely  ovate,  strongly  inflated;  umbos  high,  sub¬ 
central;  sculpture  consisting  of  irregularly  spaced  concentric  undulations 
and  obscure  narrow  radial  furrows,  usually  absent  on  central  part  of  valve ; 
cardinal  area  narrow,  amphidetic,  interrupted  by  the  shallow  triangular 
chondrophore;  hinge  consisting  of  an  uninterrupted  series  of  teeth,  posterior 
teeth  more  numerous  than  anterior,  outermost  posterior  teeth  more  hori¬ 
zontal  than  outermost  anterior,  median  teeth  vertical,  shorter  than  anterior 
and  posterior  ones;  posterior  muscle-scar  larger  than  anterior;  inner  edge  of 
margin  of  valve  smooth. 

There  are  no  Bowden  species  of  Limopsis  s.  s. 

Subgenus  PECTUNCULINA  d’Orbigny. 

d’Orbigny,  1843,  Paleontologie  Frangaise:  Terrain  Cretace,  vol.  3,  p.  182. 

Type  (by  subsequent  designation,  Sacco,  1898.) — Pectunculus 
scalaris  Sowerby.  Eocene,  London  basin. 

The  following  is  a  description  of  the  subgenus  Pectunculina : 

Shell  medium-sized,  obliquely  ovate,  moderately  inflated;  umbos  moder¬ 
ately  high,  subcentral;  sculpture  reticulate;  cardinal  area  like  Limopsis  s.  s. ; 
hinge  interrupted  under  chondrophore,  posterior  teeth  more  horizontal  than 
anterior;  posterior  muscle-scar  bounded  on  anterior  side  by  an  obscure 
radial  ray  that  becomes  stronger  toward  ventral  margin;  inner  edge  of 
margin  of  valve  finely  fluted. 

The  reticulate  sculpture,  interrupted  hinge,  and  fluted  inner  margin 
separate  Pectunculina  from  Limopsis  s.  s.  Tertiary  and  living  species 


PELECYPODS. 


55 


of  Pectunculina  are  widely  distributed  in  the  warm  seas.  Some  of 
the  Recent  species  live  in  deep  water. 

Key  to  Bowden  species  of  Pectunculina. 

Sculpture  strongly  reticulate .  L.  (P.)  ovalis  silova 

Sculpture  consisting  of  widely  spaced  concentric  threads  and  low 

radial  riblets .  L.  (P.)  jamaicensis 

Limopsis  (Pectunculina)  ovalis  silova,  new  subspecies. 

(Plate  6,  Figures  4,  5.) 

The  following  is  a  description  of  this  subspecies: 

Shell  small,  subovate,  moderately  convex,  subequilateral ;  umbos  promi¬ 
nent,  strongly  incurved ;  sculpture  consisting  of  almost  equally  strong  radial 
and  concentric  riblets;  cardinal  area  moderately  narrow;  in  front  of  the 
chondrophore  are  5  or  6  almost  vertical  teeth,  the  inner  tooth  placed  under 
the  chondrophore,  a  short  edentulous  internal  separates  the  anterior  series 
from  the  4  or  5  more  horizontal  teeth  in  the  posterior  series;  muscle-scars 
obscure;  inner  edge  of  the  anterior  margin  of  the  valve  finely  fluted,  the 
fluting  disappearing  on  the  posterior  margin. 

Length  5.8  mm.;  height  6.2  mm.;  diameter  (left  valve)  1.5  mm. 

L.  ovalis  ovalis  Gabb  was  described  from  Miocene  beds  in  the 
Dominican  Republic.  It  reaches  a  slightly  larger  size  than  the  Bow¬ 
den  subspecies  and  is  slightly  less  oblique.  On  the  type  of  Gabb’s 
species  the  concentric  sculpture  is  stronger  than  the  radial;  two 
smaller  shells  in  the  Gabb  collection  have  a  sculpture  closely  resem¬ 
bling  that  of  L.  ovalis  silova ,  but  the  radial  riblets  are  more  widely 
spaced.  L.  hatoviejonis  Maury  apparently  is  the  same  as  the  smaller 
shells  included  by  Gabb  under  L.  ovalis. 

Guppy  has  described  a  similar  Limopsis,  L.  subangularis,  from 
beds  probably  of  Miocene  age  at  Pointapier,  Trinidad.  It  is  so  similar 
to  L.  ovalis  that  it  might  be  considered  a  subspecies.  The  Trinidad 
subspecies  is  smaller  than  L.  ovalis  silova,  slightly  more  oblique,  less 
convex,  and  has  concentric  sculpture  that  is  usually  stronger  than  the 
radial.  L.  ovalis  ovalis,  L.  ovalis  silova,  and  L.  ovalis  subangularis , 
in  the  order  named,  constitute  a  series  wherein  the  shell  grades  from 
relatively  large  and  slightly  oblique  to  small  and  more  decidedly 
oblique,  but  the  differences  are  slight. 

The  living  West  Indian  Limopsis  that  goes  under  the  name  of  L. 
minuta  (Philippi)  is  more  oblique  than  L.  ovalis  silova,  more  convex, 
and  more  finely  sculptured. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352765). 

Limopsis  (Pectunculina)  jamaicensis,  new  species. 

(Plate  6,  Figures  6,  7.) 

The  following  is  a  description  of  this  species: 

Shell  minute,  heavy  for  the  size,  suborbicular;  umbos  relatively  promi¬ 
nent;  sculpture  consisting  of  fine,  widely  separated  concentric  lamellae 


56 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


(interspaces  broadest  in  the  central  part  of  shell),  and  less  prominent,  more 
closely  spaced  radial  riblets;  the  concentric  lamellae  are  thin  and  worn, 
except  on  the  radial  riblets,  where  they  are  heavier;  posterior  part  of  the 
narrow  cardinal  area  longer  than  anterior;  teeth  in  two  series,  separated 
by  a  relatively  wide  edentulous  area,  the  3  teeth  of  the  anterior  series  heavy, 
vertical,  and  placed  near  dorsal  margin;  the  3  posterior  teeth  smaller,  almost 
horizontal,  lying  farther  from  dorsal  margin,  and  placed  one  below  the 
other  in  a  gently  curved  series ;  inner  margin  of  valve  faintly  fluted,  fluting 
coarsest  at  posterior  end  of  ventral  margin. 

Length  2  mm.;  height  2.2  mm.;  diameter  (left  valve)  0.8  mm. 

This  species  is  known  only  from  the  holotype,  a  left  valve.  It 
resembles  L.  monilis  Olsson,1  from  the  Miocene  of  Costa  Rica,  but 
has  less  conspicuous  sculpture. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352766). 

Superfamily  PTERIACEA. 

Family  PINNIDAE. 

Genus  PINNA  Linne. 

Linne,  1758,  Systema  Naturae,  ed.  10,  p.  707. 

Type  (by  subsequent  designation,  Gray,  18^7.) — Pinna  rudis 
Linne.  Recent,  West  Indies  (?). 

The  following  is  a  description  of  the  genus  Pinna : 

Shell  large,  thin,  elongate  trigonal,  gaping  at  posterior  end;  umbos  ter¬ 
minal;  exterior  bearing  a  longitudinal  groove  at  the  angular  shoulder; 
sculpture  consisting  of  longitudinal  ridges;  hinge  edentulous;  inner  nacreous 
layer  cleft  opposite  shoulder  except  near  umbo,  where  there  is  a  narrow  ridge. 

Tertiary  and  living  species  of  Pinna  have  a  wide  distribution.  The 
living  species  inhabit  the  tropical  and  temperate  seas. 

Pinna  refurca,  new  species. 

(Plate  6,  Figure  8.) 

The  following  is  a  description  of  this  species: 

Shell  small,  slender,  moderately  thick,  strongly  inflated;  shoulder  of  shell 
subangular  to  rounded,  lying  nearer  dorsal  margin;  dorsal  surface  almost 
flat,  ventral  surface  gently  arched;  dorsal  and  ventral  margins  straight, 
diverging  at  an  angle  of  about  25°;  external  surface  bearing  a  relatively 
deep  grove  beginning  near  anterior  end  and  extending  along  shoulder  of 
shell;  dorsal  part  of  shell  sculptured  with  5  longitudinal  ridges,  excluding 
the  ridge  adjacent  to  the  groove;  upper  half  or  more  of  ventral  part  of 
shell  sculptured  with  3  more  irregular,  broader,  lower  ridges,  followed 
(toward  the  ventral  margin)  by  oblique,  obscure  undulations,  diverging 
slightly  from  the  margin  and  terminating  abruptly  at  the  longitudinal 
ridges;  inner  surface  of  umbonal  part  of  valve  bearing  a  narrow  ridge  corre¬ 
sponding  to  the  external  groove. 

Length  about  65  mm.  (estimated) ;  height  17.5  mm.;  diameter  (left  valve) 
7.8  mm. 


1  Comparison  based  on  figures. 


PELECYPODS. 


57 


This  species  is  described  from  two  fragments  representing  the 
middle  part  of  a  left  valve  (holotype)  and  a  small  almost  complete 
right  valve.  On  the  larger  fragment  most  of  the  posterior  muscle- 
scar  is  visible.  It  is  large,  longitudinally  elongate,  convexly  rounded 
posteriorly,  and  ventral  in  position. 

The  Caloosahatchee  species  (P.  caloosaensis  Dali)  is  heavier,  more 
symmetrical,  and  has  a  broader,  higher  internal  ridge  and  different 
sculpture.  The  living  West  Indian  species  known  as  P.  rudis  is 
thinner,  has  a  less  conspicuous  external  groove  and  internal  ridge, 
and  different  sculpture.  These  species  reach  a  larger  size  than  the 
Bowden  species. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352767). 

Genus  ATRINA  Gray. 

Gray,  1847,  Proceedings  Zoological  Society  of  London,  part  15,  p.  190. 

Type  (by  original  designation). — Pinna  nigra  Chemnitz.  Recent, 
Indo-Pacific. 

The  following  is  a  description  of  the  genus  Atrina : 

Shell  large,  thin,  elongate  trigonal  to  triangular,  gaping  at  posterior  end; 
umbos  terminal;  sculpture  consisting  of  longitudinal  ridges,  smooth  or  orna¬ 
mented  with  spines ;  hinge  edentulous. 

Atrina  is  widely  distributed  in  the  Tertiary  and,  living  faunas  of 
the  warm  and  temperate  seas.  It  has  often  been  confused  with 
Pinna. 

Atrina  species. 

(Plate  6,  Figure  9.) 

The  genus  Atrina  is  represented  by  a  broken  right  valve.  The 
ventral  margin,  apical  and  extreme  posterior  parts  are  missing,  so 
that  the  outline  is  not  known,  although  the  shell  appears  to  be  elon¬ 
gate  and  slender;  the  dorsal  margin  is  straight  and  slightly  reflexed. 
Most  of  the  external  surface  is  sculptured  with  relatively  coarse 
oblique  undulations  upon  which  are  superimposed  finer  oblique 
ridges;  but  along  the  ventral  edge,  which  may  be  some  distance  from 
the  ventral  margin,  there  are  indications  of  at  least  one  longitudinal 
ridge. 

Family  ISOGNOMONIDAE. 

Genus  ISOGNOMON  Solander. 

Solander,  1786,  A  Catalogue  of  the  Portland  Museum,  p.  9.1 

Type  (by  tautonymy). — Ostrea  isognomon  Linne.  Recent,  Indo- 
Pacific. 

The  following  is  a  description  of  the  genus  Isognomon: 

Shell  reaching  a  large  size,  obliquely  subquadrate,  posterior  end  auriculate 
or  rounded ;  anterior  margin  insinuated  by  a  narrow  byssal  gape  near  dorsal 

1  This  citation  is  given  on  the  authority  of  Iredale  (Proc.  Mai.  Soc.  London,  vol.  11,  p.  303, 
1915). 


58 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


margin;  ligament  area  bearing  numerous  parallel  grooves  perpendicular  to 
dorsal  margin  of  valve;  interior  nacreous. 

The  American  Tertiary  and  living  species  are  not  so  strongly  auri- 
culate  as  the  type  species.  This  genus,  also  known  as  Perna  and 
Melina,  is  found  in  virtually  all  Tertiary  and  living  faunas  of  the 
warm  seas.  In  Europe  it  is  represented  by  several  Tertiary  species, 
but  there  are  no  living  species  in  the  European  seas. 

Isognomon  species. 

(Plate  6,  Figure  10.) 

The  genus  Isognomon  is  represented  by  a  small  fragment  of  an 
apparently  adult  valve  and  an  almost  perfect  young  valve.  The 
larger  shell  is  very  thick  in  the  umbonal  region;  the  byssal  notch  is 
long,  abruptly  indented;  the  ligament  grooves  are  long,  diverging  at 
a  slight  angle  from  the  byssal  notch,  and  the  raised  intervals  between 
the  grooves  are  narrower  than  the  grooves;  the  sculpture  consists  of 
numerous  fine  concentric  striations,  reinforced  at  intervals  by  incre¬ 
mental.  The  small  valve  is  subquadrate  in  outline;  its  anterior 
lateral  margin  is  flexed  inward,  and  the  byssal  notch  is  indistinct ;  the 
4  ligament  grooves  are  relatively  wide,  and  separated  by  much 
narrower  ridges. 


Family  PTERIIDAE. 

Genus  PTERIA  Scopoli. 

Scopoli,  1777,  Introductio  ad  Historiam  naturalem,  sistens  genera  Lapidum, 
Plantarum  et  Animalium  hactenus  detecta,  caracteribus  essentialibus 
donata,  in  tribis  divisa,  subinde  ad  leges  Naturae,  p.  397. 

Type  (by  monotypy.) — Mytilus  hirundo  Linne.  Recent,  Mediter¬ 
ranean  Sea. 

The  following  is  a  description  of  the  genus  Pteria : 

Shell  of  varying  size,  nacreous,  posterior  and  anterior  ends  auriculate; 
anterior  margin  below  auricle  insinuated  by  a  narrow  byssal  gape ;  sculpture 
weak;  cardinal  area  narrow,  almost  as  long  as  dorsal  margin  of  valve;  right 
and  left  valve  bearing  1  or  2  small  cardinal  teeth  fitting  into  shallow 
sockets,  and  a  long  posterior  lateral  lamella. 

Pteria  has  a  long  history,  as  it  is  abundant  in  late  Paleozoic  and 
Mesozoic  deposits.  The  living  species  have  a  wide  distribution  in 
warm  and  temperate  seas. 

Pteria  inomata  (Gabb). 

(Plate  6,  Figure  11.) 

Avicula  inornata  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol.  15,  p.  253. 

Pteria  inomata  (Gabb),  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia, 
vol.  3,  part  4,  p.  669.  Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5,  pp. 
345-346,  plate  52,  fig.  14.  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.  Philadelphia, 
vol.  73,  p.  408,  plate  42,  figs.  6,  7. 


PELECYPODS. 


59 


The  following  is  the  original  description  of  this  species: 

Shell  small,  oblique,  convex;  anterior  ear  small,  triangular,  posterior  mod¬ 
erately  long,  acuminate;  surface  smooth,  without  ornament.  Length  1  inch. 

Type  locality. — Dominican  Republic. 

The  following  is  a  description  of  Bowden  specimens  of  this  species: 

Shell  small,  moderately  and  broadly  inflated  along  a  diagonal  from  the 
umbo  to  the  posterior  ventral  margin,  greatest  inflation  medial  and  rising 
abruptly  from  anterior  margin,  descending  more  gently  toward  posterior 
and  ventral  margins;  dorsal  margin  moderately  long,  straight;  umbo  low, 
scarcely  rising  above  dorsal  margin;  anterior  auricle  small,  triangular, 
depressed,  set  off  from  rest  of  shell  by  a  ledge  along  line  of  narrow  byssal 
sinus;  surface  of  the  shell  smooth  except  for  obscure  sinuous  incrementals 
on  anterior  auricle ;  cardinal  area  narrow,  long,  extending  almost  to  ends  of 
dorsal  margin;  hinge  of  right  valve  bearing  a  socket  placed  slightly  in  front 
of  umbo  and  a  lateral  lamella  near  posterior  end  of  dorsal  margin. 

Length  about  20  mm.  (estimated) ;  height  11  mm.;  diameter  (right  valve) 
3.2  mm. 

This  species  is  represented  by  a  few  broken  valves.  The  valve 
figured  is  a  little  less  inflated  and  has  a  wider  posterior  auricle  than 
most  shells  from  the  Cercado  formation  of  the  Dominican  Republic, 
which  carries  many  broken  specimens. 

Other  localities. — Cercado  formation  (lower  Miocene),  Dominican 
Republic. 

Type  material. — Holotype  (Acad.  Nat.  Sci.  Philadelphia  No.  2748). 

Superfamily  OSTRACEA. 

Family  OSTREIDAE. 

Genus  OSTREA  Linne. 

Subgenus  OSTREA  s.  s. 

Section  OSTREA  s.  s. 

Bolten,  1798,  Museum  Boltenianum,  part  2,  p.  168. 

Type  (by  subsequent  designation,  Gray,  181^7). — Ostrea  edulis 
Linne.  Recent,  seas  of  Europe. 

The  following  is  a  description  of  the  section  Ostrea  s.  s. : 

Shell  medium-sized,  irregular  in  outline,  inequilateral;  left  valve  larger, 
attached,  convex;  right  valve  flat;  left  valve  sculptured  with  numerous  low 
folds  extending  to  margin  of  valve;  right  valve  lamellar;  hinge  edentulous; 
resilium  seated  on  a  longitudinal  groove  on  left  valve  corresponding  to  a 
ridge  on  right  valve,  ligament  occupying  an  area  on  both  sides  of  resilium; 
margins  of  valve  below  ligament  area  minutely  corrugated. 

The  small  oysters  from  the  Bowden  formation  seem  to  be  similar 
to  the  type  of  the  section  Lopha. 

Section  LOPHA  Bolten. 

Bolten,  1798,  Museum  Boltenianum,  part  2,  p.  168. 

Type  (by  subsequent  designation,  Dali,  1898). — Ostrea  cristagalli 
Gmelin.  Recent,  Indo-Pacific. 


60 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  following  is  a  description  of  the  section  Lopha : 

Shell  medium-sized,  subequivalve,  subovate  to  falcate;  sculpture  of  both 
valves  similar,  consisting  of  deep  radial  folds;  inner  margin  of  valve 
minutely  pustolose ;  groove  for  resilium  on  left  valve  wide  and  very  shallow. 

Oysters  of  the  section  Lopha  are  common  in  the  tropical  seas. 

Key  to  the  Bowden  species  of  Lopha. 

Folds  subangular,  3  to  5 .  0.  (L.)  paramegodon 

Folds  angular,  5  to  7 .  0.  (L.)  guppyi 

Folds  subrounded,  15  to  20 .  O.  ( L .)  folioides 


Ostrea  (Lopha)  paramegodon,  new  species. 

(Plate  6,  Figures  12  to  14.) 

Ostrea  megodon  Dali  (part,  not  Hanley)  1898,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  4,  pp.  685-686. 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  subequivalve;  both  valves  compressed  or  slightly  convex; 
outline  variable,  elongate,  longitudinally  subovate  to  subfalcate;  left  valve 
bearing  3  to  5  broad  irregular  subangular  to  rounded  folds,  most  prominent 
at  ventral  margin  and  extending  only  a  short  distance  from  margin ;  depres¬ 
sions  between  folds  broader,  thinner,  but  less  angular  than  folds;  right  valve 
bearing  similar  but  less  prominent  folds,  or  irregularly  warped;  neither 
valve  has  definite  concentric  sculpture  except  inconspicuous,  usually  non- 
laminated  incrementals ;  ligament  area  wide,  oblique,  bearing  on  the  left 
valve  a  broad,  shallow  median  depression;  submargins  finely  pustulate; 
muscle-scar  relatively  large,  longitudinally  subelliptical  to  broadly  subovate 
in  outline,  the  anterior  dorsal  margin  deeply  emarginate. 

A  longitudinally  subovate  right  valve:  length  26.5  mm.;  height  40.5  mm. 
A  subfalcate  right  valve:  dorsal  length  17  mm.;  ventral  length  27.5  mm.; 
height  31.5  mm. 

0.  paramegodon  resembles  O.  megodon  Hanley,  a  living  species 
described  from  Peru  and  recorded  as  far  north  as  Lower  California, 
but  is  much  smaller,  less  curved,  and  has  shallower  folds.  The 
Bowden  species  seems  to  more  closely  resemble  this  living  West  Coast 
species  than  any  living  West  Indian  species.  The  somewhat  curved 
0.  pauciplicata  Dali,  from  the  Oak  Grove  sand  of  Florida,  has  a 
larger  number  of  folds  and  regular  concentric  lamellae. 

A  similar  species  from  the  Gurabo  formation  of  the  Dominican 
Republic,  described  by  Maury  as  0.  megodon ,  is  more  curved  than 
0.  paramegodon  and  has  deeper  folds;  aside  from  the  difference  in 
size  it  is  more  like  the  living  0.  megodon.  The  Miocene  species  from 
Costa  Rica,  recorded  by  Olsson  as  0.  megodon,  is  more  curved  than 
the  Bowden  species  and  has  more  numerous  folds. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352771);  paratype  (right  valve,  U.  S.  Nat.  Mus.  No.  352772). 


PELECYPODS. 


61 


Ostrea  (Lopha)  guppyi,  new  species. 

(Plate  7,  Figures  1,  2.) 

Ostrea  haitensis  Dali  (part,  not  Sowerby),  1898,  Trans.  Wagner  Free  Inst.  Sci., 
Philadelphia,  vol.  3,  pt.  4,  p.  685. 

The  following  is  a  description  of  this  species: 

Shell  small,  width  not  exceeding  30  mm.;  thin  or  slightly  thickened,  com¬ 
pressed  or  slightly  convex;  outline  varying  from  longitudinally  ovate  to 
broadly  ovate  or  even  subcircular;  left  valve  bearing  5  to  7  strong,  narrow, 
usually  sharply  angular  folds,  some  rising  near  the  umbo  and  becoming 
progressively  prominent  toward  margin;  on  some  shells  secondary  folds 
extend  a  short  distance  from  the  margin;  interspaces  between  folds  deep 
and  sharply  angular;  concentric  sculpture  consisting  of  lamellae,  superim¬ 
posed  on  the  folds  and  most  prominent  near  ventral  margin;  right  valve 
almost  smooth  or  bearing  folds  similar  to  those  on  the  left;  submargins 
usually  corrugated;  muscle-scar  large  for  the  size  of  the  shell,  subelliptical 
to  subcircular  in  outline;  inner  margin  of  the  valve  bearing  minute  pustules. 

Length  28  mm. ;  height  35  mm. 

0.  haitensis  Sowerby,  which  in  the  Dominican  Republic  is  confined 
to  the  Gurabo  formation,  has  a  very  large,  heavy  shell.  Adult  shells 
are  150  mm.  high  and  140  mm.  wide.  The  Bowden  shells  have  much 
deeper  folds  than  young  Dominican  shells  of  the  same  size.  The 
Bowden  species  more  resembles  unattached  valves  of  the  living  West 
Indian  mangrove  oyster,  0.  folium  Linne,  but  is  smaller  and  has  fewer 
folds.  0.  guppyi  also  resembles  0.  costaricensis  Olsson,1  a  Miocene 
species  from  Costa  Rica,  but  is  smaller  and  has  deeper  and  wider 
folds. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352773). 

Ostrea  (Lopha)  folioides,  new  species. 

(Plate  7,  Figures  3  to  5.) 

The  following  is  a  description  of  this  species: 

Shell  small  and  thin;  outline  variable,  longitudinal  subovate  to  elongate 
and  narrow;  left  valve  usually  more  convex  than  right;  margins  of  valves 
sculptured  with  15  to  20  sharp,  usually  subrounded  folds  extending  only  a 
short  distance  from  the  margin,  central  part  of  shell  almost  smooth  or 
bearing  curved  clasping  spines;  concentric  sculpture  consisting  of  incon¬ 
spicuous  incremental  lamellae;  ligament  area  small,  flattened;  muscle-scar 
small,  subelliptical  to  subcircular  in  outline;  inner  margin  of  shell,  or  only 
parts  of  margin,  bearing  small  pustules. 

Length  11  mm.;  height  34  mm. 

O.  folioides  superficially  resembles  the  living  West  Indian  man¬ 
grove  oyster,  O.  folium  Linne,  as  some  of  the  shells  have  clasping 
spines.  None  of  the  Bowden  shells  is  so  large  as  O.  folium  and  all 
are  less  deeply  folded  than  living  shells  of  the  same  size. 

Only  the  shells  that  were  attached  to  twigs  or  roots  have  clasping 
spines.  All  the  shells  that  are  referred  to  this  species  have  numerous 


1  Comparison  based  on  figures. 


62 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


small  marginal  folds.  The  folds  are  smaller  and  more  numerous  than 
in  0.  guppyi  and  extend  only  a  short  distance  from  the  margin  of 
the  shell. 

A  similar  species  was  collected  in  the  Dominican  Republic  from 
the  Cercado  formation  on  Rio  Mao  at  station  8525. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352774). 

Superfamily  PECTINACEA. 

Family  PECTINIDAE. 

Genus  PECTEN  Muller. 

Subgenus  PECTEN  s.  s. 

Muller,  1776,  Zoologiae  Danicae,  p.  248. 

Type  (by  subsequent  designation,  Gray,  184-7). — Ostrea  maxima 
Linne.  Recent,  northern  seas  of  Europe. 

The  following  is  a  description  of  the  subgenus  Pecten  s.  s.: 

Shell  reaching  a  large  size,  equilateral,  inequivalve;  right  valve  moder¬ 
ately  inflated,  adult  left  valve  slightly  inflated,  young  left  valve  concave; 
auricles  moderately  large,  subequal,  convex  on  right  valve,  concave  on  left; 
cardinal  edge  of  auricles  of  right  valve  bent  downward;  byssal  notch 
narrow ;  radial  sculpture  consisting  of  wide  rounded  ribs  and  narrow  threads 
on  both  ribs  and  interspaces;  concentric  sculpture  consisting  of  fine  incre¬ 
mental  lamellae;  chondrophore  large,  deep,  flanked  by  3  or  4  pairs  of 
cardinal  crura. 

Pecten  s.  s.  was  widely  distributed  in  late  Mesozoic  time.  The 
living  species  have  an  extensive  geographic  range. 

The  Bowden  species  referred  to  this  subgenus  lacks  the  radial 
threads  of  the  type  species. 

Pecten  (Pecten)  barretti,  new  species. 

(Plate  7,  Figures  6,  7.) 

Pecten  ( Pecten )  soror  Dali  (part,  not  Gabb),  1898,  Trans.  Wagner  Free  Inst. 

Sci.  Philadelphia,  vol.  3,  part  4,  p.  712. 

The  following  is  a  description  of  this  species: 

Shell  large;  dorsal  margins  slightly  concave,  diverging  at  an  angle  of 
about  95°;  right  valve  strongly  inflated,  sculptured  with  19  to  22  high, 
almost  square  ribs,  their  edges  and  tops  slightly  rounded,  separated  by 
narrower,  deeply  channeled  interspaces;  in  the  interspaces  and  on  the 
flanks  of  the  ribs  are  obscure,  fine,  slightly  raised  concentric  lamellae;  left 
valve  slightly  concave,  sculptured  with  the  same  number  of  narrower  square 
ribs,  and  deep,  flat  interspaces  of  the  same  width  or  slightly  wider;  con¬ 
centric  lamellae  more  prominent  than  on  right  valve  and  occasionally 
extending  across  ribs,  but  less  conspicuous  on  ribs  than  in  interspaces; 
submargins  relatively  wide  and  forming  a  deep  ledge  on  left  valve;  auricles 
subequal,  sculptured  with  weak  radial  ribs  and  fine  concentric  lamellae; 
interior  ventral  margin  deeply  fluted. 

Left  valve:  length  50  mm.;  height  45  mm.;  length  of  hinge  25  mm.  Im¬ 
mature  right  valve:  length  32  mm.;  height  29.5  mm.;  diameter  7  mm.; 
length  of  hinge  about  13  mm. 


PELECYPODS. 


63 


P.  barretti  resembles  P.  soror  (Gabb),  described  from  the  Domi¬ 
nican  Republic,  where  it  has  been  collected  from  both  the  Cercado 
and  Gurabo  formations.  The  Bowden  species  has  less  concave  dorsal 
margins;  the  right  valve  has  fewer  and  more  rectangular  ribs,  nar¬ 
rower  interspaces,  and  less  conspicuous  concentric  lamellae;  the  left 
valve  has  more  rectangular  ribs  and  more  strongly  sculptured  auricles. 

None  of  the  valves  of  P.  barretti  is  in  attached  position  and  the 
right  and  left  valves  here  described  may  possibly  belong  to  different 
species. 

Type  material . — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352776) ;  paratype  (left  valve,  U.  S.  Nat.  Mus.  No.  352777). 

Subgenus  EUVOLA  Dali. 

Dali,  1898,  Transactions  Wagner  Free  Institute  of  Science  of  Philadelphia,  vol. 
3,  part  4,  p.  694. 

Type  {by  original  designation). — Ostrea  ziczac  Linne.  Recent, 
West  Indies. 

The  following  is  a  description  of  the  subgenus  Euvola : 

Shell  reaching  a  large  size,  equilateral,  inequivalve;  right  valve  strongly 
inflated,  sculptured  with  narrow,  shallow  radial  grooves;  left  valve  concave, 
sculptured  with  radial  grooves  and  concentric  threads ;  auricles  large ;  byssal 
notch  narrow;  chondrophore  large,  deep,  flanked  by  a  pair  of  cardinal  crura 
near  the  cardinal  margin. 

Euvola  differs  from  Pecten  s.  s.  in  having  a  more  inflated  right 
valve,  weaker  radial  sculpture,  and  only  one  pair  of  cardinal  crura. 

Euvola  is  a  tropical  and  subtropical  group  of  Pectens.  The  earliest 
American  species  are  from  deposits  of  Miocene  age. 

Pecten  (Euvola)  bowdenensis  Dali. 

(Plate  7,  Figures  8,  9.) 

Pecten  ( Euvola )  bowdenensis  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  4,  p.  713,  plate  29,  fig.  1.  ?  Bose,  1906,  Bol.  Soc. 
Geol.  Mexicana,  vol.  1,  p.  143  (list).  ?  Bose,  1906,  Bol.  Inst.  Geol.  Mexico, 
No.  22,  p.  27,  plate  1,  figs.  8,  10. 

The  following  is  the  original  description  of  this  species: 

Shell  resembling  P.  ziczac  L.  in  the  right  valve,  with  about  23  obsolete 
smooth  ribs  separated  by  impressed  lines;  right  valve  very  convex;  ears 
subequal,  smooth,  notch  narrow,  deep;  left  valve  with  17  low,  rounded  ribs 
separated  by  wider,  squarely  impressed  interspaces;  submargins  wide, 
smooth;  disk  moderately  concave;  ears  subequal,  smooth,  concavely  arched; 
interior  margin  of  the  base  with  paired  lirae,  the  pairs  separated  by  deeper 
channels;  cardinal  crura  obvious.  Alt.,  43;  lat.,  44.5  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  thin,  width  and  length  almost  equal,  hinge-line  approximately  equal 
to  half  the  width  of  shell;  dorsal  margins  long,  slightly  concave,  diverging 


64 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


at  an  angle  of  about  105°;  outline  of  ventral  half  evenly  semicircular;  con¬ 
vex  right  valve  bearing  shallow  radial  grooves,  the  surface  more  or  less 
polished  and  bearing  very  faint,  irregularly  spaced  incremental  lamellae, 
usually  slightly  more  conspicuous  and  more  regularly  spaced  on  submargins 
and  on  irregular  somewhat  worn  areas  on  disk;  umbonal  part  of  concave 
left  valve  almost  smooth,  middle  of  the  interspaces  between  low  ribs  usually 
slightly  raised;  the  fine  concentric  threads  more  conspicuous  than  on  right 
valve  and  more  regularly  spaced;  auricles  on  both  valves  subequal  and 
smooth,  except  for  fine  incrementals,  which  are  sinuous  on  the  right  anterior 
auricle;  on  interior  of  left  valve  paired  lirae  are  visible  for  only  a  short 
distance  from  the  margin,  interval  between  two  members  of  a  pair  more 
deeply  channeled  than  interval  between  pairs;  on  right  valve  lirae  extend 
further  up  toward  the  umbo  and  the  interval  between  two  pairs  more  deeply 
channeled  than  interval  between  two  members  of  a  pair. 

A  right  valve :  length  44  mm. ;  height  45  mm. ;  diameter  16  mm. ;  length 
of  hinge  21  mm.  A  left  valve:  length  47  mm.;  height  46.2  mm.;  diameter 
6  mm. ;  length  of  hinge  22.5  mm. 

P.  bowdenensis  closely  resembles  the  living  West  Indian  species 
P.  ziczac  (Linne),  but  the  right  valve  of  the  living  species  is  not 
quite  so  inflated  and  the  left  valve  is  sculptured  with  more  numerous 
ribs,  separated  by  narrow  grooves.  P.  medius  Lamarck,  is  more 
strongly  ribbed.  The  Costa  Rican  Miocene  (?)  species  P.  limonensis 
Dali  is  smaller  and  has  weaker  sculpture.  The  interspaces  of  the  left 
valves  which  Bose  described  from  Miocene  beds  in  Tuxtepec,  Mexico, 
seem  to  be  flatter  and  deeper  than  in  P.  bowdenensis.1 

Type  material. — 9  cotypes  (1  right  and  8  left  valves,  2  of  which 
represent  Pecten  ( Pecten )  barretti,  U.  S.  Nat.  Mus.  No.  135782). 

Genus  CHLAMYS  Bolten. 

Subgenus  CHLAMYS  s.  s. 

Bolten,  1798,  Museum  Boltenianum,  pt.  2,  p.  161. 

Type  (by  subsequent  designation ,  Dali,  1898). — Pecten  islandicus 
Muller.  Recent,,  seas  of  Europe. 

The  following  is  a  description  of  the  subgenus  Chlamys  s.  s.: 

Shell  medium-sized,  inequilateral,  dorsal  margins  sloping  steeply,  left 
valve  a  little  more  inflated  than  right;  radial  sculpture  consisting  of  narrow 
ribs,  an  increasing  number  of  secondary  radials  added  as  the  shell  grows; 
concentric  sculpture  consisting  of  more  or  less  scaly  lamellae;  auricles 
unequal,  anterior  ones  larger,  right  anterior  auricle  deeply  insinuated,  pro¬ 
ducing  a  conspicuous  byssal  gape,  margin  of  valve  below  auricle  bearing  a 
ctenolium ;  cardinal  margin  of  auricles  of  both  valves  bent  inward,  the  right 
valve  more  strongly;  chondrophore  moderately  deep,  flanked  by  2  pairs  of 
cardinal  crura,  the  upper  crura  long,  especially  the  anterior  one,  the  lower 
short,  more  oblique,  and  near  the  chondrophore. 

The  steeply  sloping  dorsal  margins  and  small  posterior  auricle  are 
characteristic  features  of  the  subgenus  Chlamys  s.  s.  Living  species 
have  a  cosmopolitan  distribution.  The  tropical  species  are  smaller 


1  Comparison  based  on  figures. 


PELECYPODS. 


65 


and  more  brightly  colored  than  the  species  living  in  cooler  water. 
Tertiary  species  were  widely  distributed,  like  the  living  ones. 

Key  to  the  Bowden  species  of  Chlamys  s.  s. 


Secondary  ribs  introduced  near  middle  of  shell .  C.  (C.)  species 

Secondary  ribs  introduced  near  ventral  margin .  C.  ( C .)  vaginulus 

Secondary  ribs  absent .  C.  (C.)  bellipictus 


Chlamys  (Chlamys)  species. 

(Plate  7,  Figure  10.) 

The  following  is  a  description  of  this  species: 

Right  valve  small,  thin,  higher  than  wide,  dorsal  margins  sloping  steeply; 
sculpture  consisting  of  about  12  narrow,  rounded  ribs;  1  or  2  secondary 
radials  lie  in  the  interspaces,  rapidly  enlarging  toward  ventral  margin;  ribs 
finely  beaded  by  irregularly  spaced  concentric  lamellae;  auricles  unequal, 
sculptured  with  relatively  prominent  radials  roughened  by  overriding  con¬ 
centric  lamellae. 

Length  4  mm.;  height  5  mm.;  diameter  (right  valve)  0.5  mm. 

This  species  is  represented  by  a  right  valve  that  apparently  is  not 
full  grown. 


Chlamys  (Chlamys)  vaginulus  (Dali). 

(Plate  8,  Figures  1,  2.) 

Pecten  ( Chlamys )  ornatus  Lamarck  ?  var.  vaginulus  Dali,  1898,  Trans.  Wagner 
Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  pp.  715-716. 

Pecten  vaginulus  Dali,  Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5,  p.  350, 
plate  60,  fig.  7. 

The  following  is  the  original  description  of  this  species: 

Seven  small  valves  of  a  species  closely  resembling  P.  ornatus  were  obtained 
at  Bowden;  the  form  and  sculpture  are  practically  the  same,  but  the  ribs 
(21  to  25)  are  single,  subequal,  and  not  fasciculated,  and  are  separated  by 
simple  narrower  interspaces  not  radially  threaded.  The  young  of  ornatus, 
as  far  as  observed,  seem  always  to  have  one  or  more  interstitial  riblets.  I 
therefore  propose  for  the  present  form  the  varietal  name  of  vaginulus,  which 
may  be  raised  to  specific  rank  if  the  difference  is  confirmed  by  the  char¬ 
acters  of  adult  specimens. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  thin,  subequivalve,  suborbicular,  height  slightly  exceeding 
width,  equilateral,  excepting  auricles,  moderately  inflated;  right  valve 
usually  less  inflated  than  left;  both  valves  sculptured  with  21  to  25  slender, 
square  to  subrounded  ribs,  separated  by  narrower  interspaces;  near  the 
ventral  margin  of  adult  shells  a  fine  radial  thread  lies  in  the  interspaces; 
in  the  interspaces  and  occasionally  overriding  the  ribs  are  fine,  inconspicuous 
concentric  lamellae;  submargins  without  radial  sculpture,  or  sculptured  with 
fine  radials,  forming  a  continuous  series  with  those  on  the  disk;  hinge  long, 
auricles  very  unequal,  especially  on  right  valve;  byssal  notch  deep  &nd 
sharply  sinuated;  both  auricles  sculptured  with  irregular  radial  ribs  and 


66 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


concentric  lamellae,  sculpture  on  the  anterior  auricle  coarser  and  more 
imbricate. 

A  right  valve:  length  11.8  mm.;  height  12  mm.;  diameter  1.9  mm.;  length 
of  hinge  7.5  mm.  A  left  valve:  length  12  mm.;  height  13  mm.;  diameter 
2.1  mm.;  length  of  hinge  7.2  mm. 

The  outline  of  the  shell  is  variable,  as  some  are  more  orbicular  than 
others.  On  some  valves  the  anterior  submargin  is  narrower  than  the 
posterior,  and  has  no  radial  sculpture.  The  posterior  submargin  may 
or  may  not  have  radial  sculpture.  Immature  right  valves  are  flat  and 
have  unusually  long  anterior  auricles. 

This  species  is  smaller  and  has  wider  umbos  than  the  living  West 
Indian  species  C.  ornatus  (Lamarck).  The  thread  in  the  interspaces 
is  smaller  than  in  the  living  species  and  is  introduced  at  a  later  stage. 
Maury  has  recorded  C.  vaginulus  Dali  from  Miocene  beds  in  the 
Samba  Hills,  Dominican  Republic.  A  broken  valve,  apparently  C. 
vaginulus ,  was  collected  by  the  U.  S.  Geological  Survey  expedition 
from  the  Gurabo  formation  on  Rio  Yaque  del  Norte  near  Santiago 
(station  8726).  The  concentric  lamellae  on  the  Dominican  shell  are 
more  crowded  and  less  conspicuous  on  the  ribs. 

Other  localities. — Gurabo  formation  (middle  Miocene),  Dominican 
Republic. 

Type  material. — 7  cotypes  (U.  S.  Nat.  Mus.  No.  135786). 

Chlamys  (Chlamys)  bellipictus,  new  species. 

(Plate  8,  Figure  3.) 

The  following  is  a  description  of  this  species: 

Right  valve  small,  thin,  compressed,  height  slightly  exceeding  width; 
dorsal  margins  long;  radial  sculpture  consisting  of  11  low,  rounded  ribs, 
separated  by  wider  interspaces,  disappearing  on  dorsal  half  of  shell;  con¬ 
centric  sculpture  consisting  of  fine,  microscopic  concentric  threads  over 
entire  surface;  auricles  subequal,  right  anterior  auricle  sculptured  with 
radials  and  superimposed  concentric  lamellae,  scaly  along  hinge;  byssal 
notch  prominent;  interior  of  valve  bearing  broad  radial  undulations  corre¬ 
sponding  to  external  intercostal  spaces ;  left  valve  not  known. 

Length  7  mm.;  height  7.5  mm. 

This  species  is  represented  by  a  small  right  valve.  Dali  has 
described  a  similar  species,  C.  alumensis,  from  the  Chipola  formation ; 
it  is  more  inflated  and  has  more  numerous  ribs. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352780). 

Subgenus  AEQUIPECTEN  Fisher 
Section  AEQUIPECTEN  s.  s. 

Fischer,  1887,  Manuel  de  Conchyliologie,  p.  944. 

Type  ( by  monotypy) . — Ostrea  opercularis  Linne.  Recent,  seas  of 
Europe. 


PELECYPODS. 


67 


The  following  is  a  description  of  the  section  Aequipecten : 

Shell  medium-sized,  left  valve  more  inflated  than  right,  umbos  narrow; 
radial  sculpture  consisting  of  relatively  wide  ribs  and  fine  grooves  on  ribs 
and  interspaces ;  auricles  subequal,  cardinal  margin  of  right  auricles  strongly 
bent  downward,  cardinal  margin  of  left  auricles  not  bent;  chondrophore 
wide,  shallow,  flanked  by  a  pair  of  upper  cardinal  crura. 

The  dorsal  margins  slope  less  steeply  than  in  Chlamys  s.  s.;  the 
auricles  are  subequal;  and  secondary  radials  are  not  intercalated  in 
the  interspaces  as  the  shell  grows. 

Tertiary  and  living  species  of  Aequipecten  are  widely  distributed. 

Chlamys  (Aequipecten)  plurinominis  morantensis,  new  subspecies. 

(Plate  8,  Figures  4,  5.) 

Pecten  exasperatus  Guppy  (not  Sowerby),  1866,  Quart.  Jour.  Geol.  Soc. 
London,  vol.  22,  p.  294.  Guppy  (part,  not  Sowerby),  1874,  Geol.  Mag. 
dec.  2,  vol.  1,  p.  443  (list). 

Pecten  ( Aequipecten )  thetidis  Dali  (part,  not  Sowerby),  1898,  Trans.  Wagner 
Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  pp.  714-715. 

The  following  is  a  description  of  this  subspecies: 

Shell  medium-sized,  subequivalve,  both  valves  moderately  convex,  sub- 
orbicular;  sculpture  similar  on  both  valves,  consisting  of  18  to  20  radial 
ribs,  more  or  less  square  on  dorsal  half  of  shell,  broader  and  more  rounded 
on  ventral  half,  separated  by  narrower  interspaces;  ribs  and  interspaces  on 
ventral  half  of  shell  ornamented  with  radial  rows  of  short,  blunt  scales, 
smaller  in  the  interspaces,  inconspicuous  on  dorsal  half  of  shell,  reduced  to 
a  single  row  and  often  absent  in  interspaces;  submargins  sculptured  with 
fine,  narrow,  irregularly  spaced  scaly  radial  ribs;  auricles  broad,  the  anterior 
longer,  sculptured  with  scaly  radial  ribs  of  irregular  width,  wider  and  higher 
than  those  on  submargins,  on  the  right  anterior  auricle  the  ribs  are  wider 
and  the  scales  more  prominent;  interior  of  shell  bearing  paired  lirae  sepa¬ 
rated  by  excavated  intervals. 

A  right  valve:  length  34.5  mm.;  height  34.4  mm.;  diameter  8  mm.;  length 
of  hinge  23.5  mm.  A  left  valve:  length  33.2  mm.;  height  34  mm.;  diameter 
8.8  mm. ;  length  of  hinge  24.5  mm. 

C.  plurinominis  morantensis  closely  resembles  C.  plurinominis 
plurinominis  Pilsbry  and  Johnson,  the  type  of  which  is  in  the  Gabb 
collection  from  the  Dominican  Republic.  The  Dominican  species 
has  been  collected  from  both  the  Cerado  and  Gurabo  formations,  but 
all  the  large  specimens,  which  are  similar  to  Gabb’s  specimens,  come 
from  the  Gurabo  formation.  The  Bowden  subspecies  has  scales  that 
are  not  so  clearly  arranged  in  radial  rows  and  the  interspaces  near  the 
ventral  margin  of  the  shell  are  narrower. 

The  Dominican  species  has  been  described  under  a  number  of 
names.  Gabb  and  Guppy  called  it  C.  oxygonum  Sowerby;  Dali  and 
Maury  called  it  C .  thetidis  Sowerby.  No  figures  accompany  Sow- 
erby’s  descriptions  of  C.  oxygonum  and  C.  thetidis,  both  of  which 
were  described  from  the  Dominican  Republic.  There  seems  to  be  no 
doubt  about  the  features  of  C.  oxygonum,  and  specimens  in  the  Gabb 
collection  agree  with  Sowerby’s  description  of  C.  thetidis.  Pilsbry 


68 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


and  Johnson  have  accordingly  renamed  the  species  P.  plurinominis. 
C.  thedites  is  more  inequilateral  than  C.  plurinominis,  and  has  higher 
ribs  that  have  a  median  groove  and  are  bounded  on  both  sides  by 
radial  threads;  the  radials  are  roughened  by  irregularly  spaced  con¬ 
centric  lamellae. 

Cooke  has  described  under  the  name  of  P.  thetidis  Sowerby  a 
species  from  the  upper  Oligocene  limestone  of  Anguilla  that  closely 
resembles  C.  plurinominis  morantensis,  but  the  Anguillan  species  is 
much  smaller  and  the  scales  are  arranged  in  prominent  radial  series 
near  the  ventral  margin  of  the  valve. 

C.  plurinominis  morantensis  is  similar  to  the  living  West  Indian 
species  C.  exasperatus  (Sowerby),  but  is  smaller,  more  orbicular,  less 
inflated,  and  has  scales  that  are  not  so  clearly  arranged  in  radial 
series.  It  more  closely  resembles  C.  juscopurpureus  (Conrad),  a 
living  species  from  Florida,  but  is  smaller  and  has  wider  and  more 
inflated  umbos. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352781) ;  paratype  (left  valve,  U.  S.  Nat.  Mus.  No.  352782). 

Section  PLAGIOCTENIUM  Dali. 

Dali,  1898,  Transactions  Wagner  Free  Institute  of  Science  of  Philadelphia, 
vol.  3,  part  4,  p.  696. 

Type  (by  original  designation). — Pecten  ventricosus  Sowerby. 
Recent,  Pacific  coast  of  Mexico  and  Central  America. 

The  following  is  a  description  of  the  section  Plagioctenium : 

Shell  reaching  a  large  size,  inequilateral,  more  elongate  at  posterior  end, 
strongly  inflated,  right  valve  more  inflated  than  left,  umbos  wide;  sculpture 
consisting  of  flat-topped  or  rounded  ribs,  separated  by  narrower  squarely 
channeled  interspaces;  looped  concentric  threads,  concave  upward,  cross  the 
interspaces;  auricles  long,  resembling  those  of  Aequipecten,  the  radial  ribs 
stronger  on  anterior  auricle  than  on  posterior,  especially  on  right  valve; 
cardinal  margin  of  right  valve  strongly  bent  downward,  as  in  Aequipecten; 
cardinal  crura  more  slender  than  in  Aequipecten. 

The  valves  of  Plagioctenium  are  more  inequilateral  than  in 
Aequipecten;  the  umbos  are  fuller  and  wider;  the  ribs  and  inter¬ 
spaces  have  no  radial  grooves ;  and  the  auricles  are  longer. 

Species  of  Plagioctenium  are  very  abundant  in  American  Tertiary 
and  living  faunas.  They  are  abundant  in  other  parts  of  the  world, 
but  usually  are  called  Chlamys  or  Aequipecten. 

Key  to  the  Bowden  species  of  Plagioctenium. 


Ribs  high,  flattened,  numbering  17  or  18  on  both  valves .  C.  ( P .)  uselmae 

Ribs  moderately  high,  rounded. 

Concentric  lamellae  strongly  elevated  in  interspaces,  ribs  numbering  17  on 

left  valve .  C.  ( P .)  concinnatus 

Concentric  lamellae  not  strongly  elevated  in  interspaces. 

Ribs,  relatively  wide,  numbering  21  to  23  on  both  valves . C.  (P.)  ameleus 

Ribs  narrow,  numbering  17  or  18  on  left  valve .  C.  (P.)  mansfieldi 

Ribs  moderately  high,  subangular  near  ventral  margin,  numbering  22  or  23  on 

right  valve,  18  or  19  on  left  valve .  C.  (P.)  gonioides 


PELECYPODS. 


69 


Chlamys  (Plagiocetenium)  uselmae  (Pilsbry  and  Johnson). 

(Plate  8,  Figures  6,  7.) 

Pecten  inaequalis  Guppy  (not  Sowerby),  1866,  Quart.  Jour.  Geol.  Soc.  London, 
vol.  22,  p.  294,  plate  18,  fig.  6.  Guppy  (part,  not  Sowerby),  1874,  Geol. 
Mag.  dec.  2,  vol.  1,  p.  443  (list). 

Pecten  ( Aequipecten )  inaequalis  Dali  (part,  not  Sowerby),  1898,  Trans. 
Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  p.  714. 

Pecten  uselmae  Pilsbry  and  Johnson,  1917,  Proc.  Acad.  Nat.  Sci.  Philadelphia, 
vol.  69,  p.  194.  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  73, 
p.  412,  plate  45,  fig.  9. 

The  following  is  the  original  description  of  this  species : 

The  shell  is  inequilateral,  inequivalve,  the  left  valve  is  larger,  conspicu¬ 
ously  surpassing  the  right  throughout  the  lower  margin  and  ends.  It  is 
strongly  convex;  the  right  valve  weakly  so.  Sculpture  of  17  rounded  ribs. 
In  the  left  valve  these  are  wider  than  the  intervals,  which  are  deeply  cut, 
with  concave  bottoms,  which  are  closely  sculptured  with  delicate  transverse 
threads.  In  the  right  valve  the  ribs  are  lower,  and  not  quite  as  wide  as  the 
intervals,  in  which  the  transverse  striation  is  often  weak.  The  submargins 
are  smooth.  Ears  with  several  ribs.  Ctenolium  is  very  short,  of  3  teeth, 
which  are  small  in  adult  shells.  Cardinal  crura  strong,  vertically  striate. 
Length  of  left  valve  28,  alt.  27.3,  diam  8.25  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  medium-sized,  height  and  width  almost  equal,  posterior  side  more 
extended;  right  valve  decidedly  inflated,  left  valve  moderately  or  slightly 
inflated,  compressed  toward  ventral  margin;  dorsal  margins  straight  or 
slightly  concave,  posterior  margin  longer  and  sloping  more  steeply  than 
anterior;  right  valve  sculptured  with  17  or  18  high,  broad,  more  or  less 
polished  radial. ribs,  their  tops  slightly  rounded  and  their  flanks  excavated; 
intercostal  spaces  narrower  than  ribs,  deeply  and  squarely  channeled,  bear¬ 
ing  concentric  lamellae;  ribs  unornamented,  but  at  their  lower  ends  irregu¬ 
larly  spaced  arched  incrementals  usually  are  visible;  left  valve  sculptured 
with  same  number  of  ribs,  but  they  are  lower  than  on  right  valve,  more 
rounded,  and  near  ventral  margin  have  sloping  sides;  interspaces  wider 
than  ribs;  concentric  lamellae  in  interspaces  and  incrementals  on  ribs  more 
prominent  than  on  the  right  valve;  submargins  on  both  valves  smooth, 
except  for  very  fine  concentric  lamellae ;  auricles  subequal,  the  posterior  one 
sculptured  with  2  to  5  small  radial  ribs,  decreasing  in  prominence  from 
margin  of  disk  or  absent  on  dorsal  part,  entire  surface  covered  with  fine 
concentric  lamellae;  anterior  auricle  sculptured  with  3  to  5  usually  slightly 
coarser  ribs  of  irregular  width,  slightly  roughened  by  inconspicuous  concen¬ 
tric  lamellae;  cardinal  crura  prominent;  interior  ventral  margin  deeply 
fluted. 

A  right  valve:  length  25.6  mm.;  height  25.5  mm.;  diameter  8  mm.;  length 
of  hinge  13  mm.  A  left  valve:  length  26.5  mm.;  height  25.8  mm.;  length 
of  hinge  14  mm. 

This  species  is  the  most  abundant  Bowden  Pecten.  The  right  valve 
is  strongly  inflated ;  the  left  valve  is  less  inflated  or  even  compressed, 
especially  on  young  shells.  The  most  inflated  shells  are  less  orbicular, 
as  they  are  higher  than  wide.  The  difference  in  radial  sculpture  on 


70 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


the  two  valves  is  striking.  On  the  left  valve,  as  the  interspaces  are 
wider  than  on  the  right,  the  concentric  sculpture  is  more  prominent 
and  the  arched,  crowded  growth-lines  on  the  ribs  are  more  uniform. 
Left  valves  are  usually  more  inequilateral  than  right  ones.  The  ribs 
of  immature  left  valves  are  less  rounded  near  the  ventral  margin 
than  on  adults;  young  right  valves  differ  from  adults  in  having  lower 
ribs  and  wider  interspaces. 

C.  inaequalis  was  described  by  Sowerby  from  the  Dominican 
Republic,  where  it  has  since  been  collected  from  the  Gurabo  forma¬ 
tion.  It  reaches  a  larger  size  than  C.  uselmae;  left  valves  of  C. 
uselmae  are  very  similar  to  left  valves  of  C.  inaequalis,  but  the  ribs 
of  right  valves  of  C.  uselmae  are  higher,  flatter,  and  have  excavated 
flanks.  C.  costaricensis  (Olsson),1  a  Miocene  species  from  Costa  Rica, 
is  very  similar,  but  is  less  inequilateral,  and  has  lower  ribs.  Young 
shells  of  C.  uselmae  closely  resembles  C.  mayaguezensis,  a  living 
species  described  by  Dali  and  Simpson  from  Porto  Rico,  but  the  ribs 
of  right  valves  of  the  Bowden  species  are  lower  and  not  so  square. 

Type  material. — Holotype  (right  valve,  Acad.  Nat.  Sci.  Philadel¬ 
phia,  No.  11124). 

Chlamys  (Plagioctenium)  concinnatus,  new  species. 

(Plate  8,  Figure  8.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  slightly  inequilateral;  left  valve  moderately  inflated, 
sculptured  with  17  strong,  almost  fiat-topped  ribs,  separated  by  interspaces 
of  virtually  same  width  as  ribs;  concentric  sculpture  consisting  of  fine, 
sharply  raised  lamellae,  overriding  ribs  except  on  lower  half  of  shell; 
lamellae  arched  in  interspaces,  with  the  convex  side  toward  ventral  margin; 
submargins  sculptured  with  concentric  lamellae,  finer  than  those  on  disk; 
auricles  subequal,  radially  and  concentrically  sculptured;  cardinal  crura 
prominent;  right  valve  not  known. 

Left  valve:  length  14.5  mm.;  height  14.7  mm.;  diameter  2.6  mm.;  length 
of  hinge  7.5  mm.  (estimated). 

This  species  is  known  only  from  the  holotype,  a  left  valve.  The 
strong,  subrounded  radial  ribs  and  conspicuous  concentric  lamellae 
over  the  entire  surface  of  the  disk,  except  on  the  lower  part  of  the 
ribs,  distinguish  it  from  other  Bowden  Plagiocteniums. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352784). 

Chlamys  (Plagioctenium)  ameleus,  new  species. 

(Plate  8,  Figure  9.) 

The  following  is  a  description  of  this  species: 

Shell  small,  subequivalve,  suborbicular,  the  two  valves  equally  inflated; 
both  valves  sculptured  with  21  to  23  strong,  subrounded  ribs,  separated  by 
narrower  interspaces;  concentric  sculpture  of  fine  lamellae  usually  appears 


1  Comparison  based  on  figures. 


PELECYPODS. 


71 


in  interspaces  and  occasionally  on  ribs,  absent  on  submargins;  auricles  un¬ 
equal,  both  bearing  inconspicuous  radials;  on  the  posterior  auricle  the 
radials  are  more  prominent  ventrally,  but  on  the  anterior  auricle  they  are 
broader  and  stronger  dorsally,  overridden  by  fine  concentric  lamellae, 
coarser  and  more  irregular  on  the  anterior  auricle. 

A  right  valve:  length  15  mm.;  height  14.8  mm.;  diameter  3.2  mm.;  length 
of  hinge  8  mm.  A  left  valve:  length  13.5  mm.;  height  13.2  mm.;  diameter 
3.5  mm. ;  length  of  hinge  6.2  mm. 

Some  shells  are  slightly  less  rounded  than  the  holotype.  On  some 
shells  a  slight  groove  lies  on  the  extreme  lower  part  of  a  few  ribs. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352785). 

Chlamys  (Plagioctenium)  mansfieldi,  new  species. 

(Plate  8,  Figure  10.) 

The  following  is  a  description  of  this  species: 

Left  valve  small,  moderately  inflated,  suborbicular,  subequilateral ;  radial 
sculpture  consisting  of  17  or  18  narrow,  square  ribs  separated  by  deeply 
channeled  interspaces  slightly  wider  than  ribs;  concentric  sculpture  con¬ 
sisting  of  widely  spaced  lamellae  overriding  radials  except  on  umbo ;  auricles 
subequal,  sculptured  with  4  or  5  radial  ribs  overridden  by  concentric 
lamellae;  right  valve  not  known. 

Left  valve:  length  8  mm.;  height  8  mm.;  diameter  1.4  mm.;  length  of 
hinge  6  mm. 

C.  mansfieldi  is  represented  by  a  few  valves,  probably  none  of 
which  is  full  grown.  It  is  less  inflated  than  C.  ameleus  and  has 
narrower  and  more  rectangular  ribs  and  more  widely  spaced  concen¬ 
tric  lamellae. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352786). 

Chlamys  (Plagioctenium)  gonioides,  new  species. 

(Plate  8,  Figures  11,  12.) 

Pecten  ( Aeqiripecten )  oxygonum  Dali  (part,  not  Sowerby),  1898,  Trans. 

Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  pp.  713-714. 

The  following  is  a  description  of  this  species: 

Shell  small,  subequivalve,  suborbicular,  posterior  end  slightly  more  ex¬ 
tended  and  unevenly  rounded ;  posterior  dorsal  margin  longer  than  anterior ; 
right  valve  sculptured  with  22  or  23  subangular  radial  ribs,  their  summit 
slightly  rounded,  on  adult  shells  the  ribs  are  rounded  at  the  ventral  margin, 
ribs  separated  by  subangular  interspaces ;  on  the  slope  of  ribs  and  in  bottom 
of  interspaces  are  fine,  closely  spaced  concentric  lamellae,  usually  not  rising 
above  summits  of  ribs;  left  valve  sculptured  with  18  or  19  similar  but 
broader  and  more  sharply  angular  ribs  and  similar  concentric  lamellae;  sub¬ 
margins  of  both  valves  smooth,  except  for  fine,  inconspicuous  concentric 
lamellae ;  auricles  subequal,  sculptured  with  4  or  5  narrow,  unequally  spaced 
radial  ribs  crossed  by  concentric  lamellae;  cardinal  crura  large. 

A  left  valve:  length  14  mm.;  height  14.1  mm.;  diameter  3.2  mm.;  length 
of  hinge  8.2  mm.  A  right  valve:  length  12.3  mm.;  height  12.2  mm.;  diam¬ 
eter  3  mm.;  length  of  hinge  6  mm. 


72 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  two  valves  are  almost  equally  inflated,  but  most  left  valves 
are  slightly  less  inflated  and  more  inequilateral.  The  radial  sculpture 
on  the  two  valves  is  quite  different;  on  the  left  valve  the  ribs  are 
fewer,  broader,  and  more  distinctly  angular,  though  slightly  rounded 
especially  at  the  ventral  margin  and  in  the  umbonal  region.  The 
concentric  lamellae  rarely  override  the  ribs.  Two  large  right  valves, 
larger  than  the  holotype,  have  ribs  that  are  rounded  and  even  flat¬ 
tened  at  the  ventral  margin.  As  usual,  young  shells  are  more  rounded 
than  adults. 

C.  gonioides  closely  resembles  C.  oxygonum  described  by  Sowerby 
from  the  Dominican  Republic.  The  U.  S.  Geological  Survey  expedi¬ 
tion  collected  from  the  Cercado  formation  on  Rio  Mao  (station 
8521)  a  valve  that  agrees  with  Sowerby’s  description.  The  Bowden 
species  has  less  angular  ribs  and  interspaces,  shallower  interspaces, 
and  weaker  concentric  sculpture. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No. 
352787);  paratype  (right  valve,  U.  S.  Nat.  Mus.  No.  353076). 

Subgenus  PALLIOLUM  Monterosato. 

Monterosato,  1884,  Nomenclatura  generica  e  specifica  di  alcune  conchiglie 
Mediterranee,  p.  5. 

Type  ( by  subsequent  designation ,  Cossmann  and  Peyrot,  1912). — 
Pecten  testae  Bivona.  Recent,  Mediterranean  Sea. 

The  following  is  a  description  of  the  subgenus  Palliolum : 

Shell  small,  thin,  equivalve,  slightly  inflated;  anterior  auricles  longer  than 
posterior,  right  anterior  auricle  sculptured  with  coarser  radial  threads  than 
left  anterior  auricle,  and  bearing  a  prominent  byssal  notch;  ctenolium 
present;  sculpture  consisting  of  fine,  slightly  roughened  vermicular  mark¬ 
ings  bent  upward  at  ends  of  shell;  cardinal  crura  absent;  interior  of  shell 
smooth. 

The  Bowden  species  described  by  Dali  as  Pecten  ( Pseudamusium ) 
guppyi  is  difficult  to  place.  It  bears  no  resemblance  to  Pecten 
hybridus  Gmelin,  the  type  of  Pseudamusium  H.  and  A.  Adams.* 1 
Pectens  of  this  type  are  placed  in  Cyclopecten  Verrill  by  some  writers, 
although  they  are  not  similar  to  Cyclopecten  pustulosus  Verrill,  the 
type  species.2  They  are  more  similar  to  Pecten  testae,  the  type  of 
Palliolum,  but  have  less  unequal  auricles,  no  ctenolium,  and  a  con¬ 
spicuously  striated  provinculum. 

Chlamys  (Palliolum?)  guppyi  (Dali). 

(Plate  8,  Figures  13  to  16.) 

Pecten  ( Pseudamusium )  guppyi  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  4,  pp.  718,  755,  plate  34,  figs.  12,  13. 

The  following  is  the  original  description  of  this  species: 

1  Type  designated  by  Suter  1913.  Pecten  exoticus  Chemnitz,  which  is  said  to  be  the  same  as 
Pecten  'pseudamusium  Sowerby,  is  usually  given  as  the  type,  but  it  is  not  in  the  original  list  of 
H.  and  A.  Adams. 

1  Type  designated  by  Suter,  1913. 


PELECYPODS. 


73 


Shell  small,  suborbicular,  moderately  convex,  smooth,  with  the  surface 
covered  with  microscopic  Camptonectes  striation;  ears  small,  the  anterior 
slightly  larger,  all  with  very  minute  radiation  and  concentric  lines;  notch 
narrow,  small,  with  no  ctenolium;  interior  smooth,  without  lirae  or  de¬ 
veloped  crura;  traces  of  the  auricular  crura  alone  perceptible;  cardinal 
margin  bearing  a  sharply  cross-striated,  very  distinct  pro  vinculum;  basal 
margins  flattened,  posterior  margin  slightly  compressed.  Alt.  6,  lat.  6  mm. 

Type  locality. — Bowden,  Jamaica. 

On  the  right  valve  the  anterior  auricle  is  larger  than  the  posterior 
and  is  sculptured  wTith  relatively  coarse  radial  threads  crossed  by 
fine  concentric  lamellae.  On  the  left  valve  the  auricles  are  subequal 
and  sculptured  with  fine  radial  threads  and  concentric  lamellae. 
Some  right  valves  have  an  anterior  and  posterior  radial  thickening, 
resembling  ribs,  on  the  interior. 

A  similar  species  from  the  Cercado  formation  of  the  Dominican 
Republic  is  smaller,  more  inflated  and  less  elongate  dorso-ventrally. 
A  fragmentary  valve  resembling  C.  guppyi  was  collected  from  the 
Gurabo  formation  of  the  Dominican  Republic.  C.  guppyi  closely 
resembles  C.  aotus  (Olsson),  a  Miocene  species  from  Costa  Rica,  but 
is  larger  and  the  auricles  of  the  left  valve  have  distinct  sculpture. 

Type  material. — 2  cotypes  (U.  S.  Nat.  Mus.  No.  135779). 

Genus  AMUSIUM  Bolten. 

Subgenus  AMUSIUM  s.  s. 

Bolten,  1798,  Museum  Boltenianum,  part  2,  p.  165. 

Type  (by  subsequent  designation,  Dali,  1886.) — Ostrea  pleuro - 
nectes  Linne.  Recent,  China  Sea. 

The  following  is  a  description  of  the  subgenus  Amusium  s.  s. : 

Shell  reaching  a  large  size,  thin,  suborbicular,  slightly  inflated,  right 
valve  slightly  more  inflated  than  left;  radial  sculpture  absent  on  exterior; 
auricles  subequal;  byssal  notch  very  small,  ctenolium  absent;  disk  and 
auricles  bearing  very  fine  incrementals ;  chondrophore  moderately  large, 
shallow,  flanked  by  2  pairs  of  cardinal  crura,  lower  much  shorter  and 
weaker  than  upper;  interior  sculptured  with  narrow  paired  ribs  that  fail 
to  reach  ventral  margin  of  valve. 

The  smooth  exterior  and  ribbed  interior  are  characteristic  features 
of  Amusium.  Its  present  distribution  (West  Indies,  Pacific,  and 
Indo-Pacific)  is  less  extensive  than  its  distribution  during  Tertiary 
time,  when  it  lived  in  virtually  all  warm  seas. 

Amusium  (Amusium)  papyraceum  (Gabb)? 

(Plate  9,  Figures  1,  2.) 

Pleuronectia  papyracea  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  new  ser.,  vol. 
15,  p.  257. 

Amusium  papyraceum  (Gabb),  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  4,  pp.  718,  719.  Maury,  1917,  Bull.  Amer 
Paleontology,  vol.  5,  p.  354,  plate  26,  fig.  22.  Maury,  1920,  Scientific 


74 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Survey  of  Porto  Rico  and  the  Virgin  Islands,  vol.  3,  part  1,  p.  21,  N.  Y. 
Acad.  Sci.  ?  Hubbard,  1921,  Scientific  Survey  of  Porto  Rico  and  the 
Virgin  Islands,  vol.  3,  part  2,  p.  96,  N.  Y.  Acad.  Sci.  Pilsbry,  1922,  Proc. 
Acad.  Nat.  Sci.  Philadelphia,  vol.  73,  p.  413,  plate  43,  figs.  8,  9. 

The  following  is  the  original  description  of  this  species: 

Shell  discoidal,  sub-circular,  very  slightly  longer  than  wide;  slightly 
inequivalve;  ears  nearly  equal;  surface  perfectly  smooth,  or  marked  only 
by  faint  lines  of  growth;  internal  surface  marked  with  small  radiating  ribs. 
Length  from  beak  to  base  2.2  inch,  width  2  inches. 

Type  locality. — Dominican  Republic. 

The  collections  from  Bowden  contain  small  pieces  of  a  large 
Amusium  and  2  broken  immature  valves.  The  pieces  show  that  the 
ventral  part  of  the  exterior  is  smooth,  except  for  faint,  closely  spaced 
incrementals,  and  the  interior  is  sculptured  with  paired  ribs.  These 
fragments  are  too  imperfect  for  accurate  identification,  but  are  very 
similar  to  A.  papyraceum.  In  the  Dominican  Republic  A.  papyra- 
ceum  has  been  collected  from  both  the  Cercado  and  Gurabo  forma¬ 
tions.  It  has  a  somewhat  ovate  outline  and  polished  exterior.  The 
Miocene  and  Pliocene  North  American  species  A.  mortoni  Ravenel 
usually  is  larger  and  more  orbicular.  A.  luna  Brown  and  Pilsbry, 
described  from  the  Gatun  formation  of  the  Canal  Zone,  has  strongly 
depressed  and  smaller  auricles. 

Fragmentary  valves  from  the  San  Sebastian  shale  (middle  Oligo- 
cene)  of  Porto  Rico,  and  other  beds  whose  name  and  age  are  not 
given,  are  referred  to  this  species  by  Maury  and  Hubbard. 

Other  localities. — Cercado  (lower  Miocene)  and  Gurabo  (middle 
Miocene)  formations,  Dominican  Republic. 

Type  material. — Holotype  (Acad.  Nat.  Sci.  Philadelphia,  No.  2864). 

Subgenus  PARVAMUSSIUM  Sacco. 

Sacco,  1897,  I  Molluschi  dei  Terreni  Terziarii  del  Piemonte  e  della  Liguria, 
part  24,  p.  48. 

Type  (by  original  designation). — Pecten  duodecim-lamellatus 
Bronn.  Miocene  and  Pliocene,  Italy. 

The  following  is  a  description  of  the  subgenus  Parvamussium : 

Shell  small,  thin,  higher  than  wide,  both  valves  moderately  inflated; 
external  sculpture  of  both  valves  consisting  of  fine  concentric  threads; 
auricles  subequal;  internal  sculpture  consisting  of  radial  ribs  that  do  not 
quite  reach  the  ventral  margin;  chondrophore  small,  flanked  by  a  pair  of 
obscure  cardinal  crura. 

The  small,  thin  shell  and  unpaired  internal  ribs  are  characteristic 
features  of  Parvamussium.  American  Tertiary  species  usually  have 
been  referred  to  Propeamusium  de  Gregorio.  Pecten  ceciliae  de 
Gregorio,  the  type  species  of  Propeamusium,  is  much  larger  and  has 
no  internal  ribs. 


PELECYPODS. 


75 


Amusium  (Parvamussium)  spendulum,  new  species. 

(Plate  9,  Figures  3,  4.) 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  compressed,  suborbicular,  higher  than  wide;  dorsal 
margins  sloping  steeply;  external  surface  of  left  valve  sculptured  with 
very  fine  concentric  threads,  disappearing  toward  ventral  margin  and  re¬ 
placed  by  a  few  faint,  coarser,  more  widely  spaced  threads;  dorsal  half 
of  shell  bearing  very  fine  radial  striae,  barely  visible  under  the  microscope; 
entire  surface  covered  with  camptonectes  striations;  internal  ribs  visible 
from  exterior;  auricles  small,  bearing  a  median  broad  ridge,  separated  from 
the  disk  by  a  slightly  depressed  groove;  interior  sculptured  with  11  rela¬ 
tively  heavy  ribs,  extending  about  half  the  distance  to  the  umbo,  thickened 
toward  ventral  margin,  but  terminating  before  margin  is  reached;  upper 
extremities  of  ribs  acute,  except  the  two  nearest  the  dorsal  margin,  which 
are  rounded;  right  valve  not  known. 

Length  5.8  mm.;  width  6.1  mm. 

This  species  is  remarkably  similar  to  A.  (P.)  pourtalesianus  (Dali), 
one  of  the  most  common  of  the  deeper  water  species  in  the  Gulf  and 
West  Indian  waters.  The  living  species  is  larger,  more  orbicular,  and 
has  larger  auricles,  and  less  conspicuous  external  sculpture;  the 
internal  ribs  are  not  quite  so  heavy,  less  swollen,  and  extend  farther 
toward  the  umbo. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352788). 

Family  SPONDYLIDAE. 

Genus  SPONDYLUS  Linne. 

Linne,  1758,  Systema  Naturae,  ed.  10,  p.  690. 

Type  (by  subsequent  designation,  Gray,  184-7). — Spondylus  gaede- 
ropus  Linne.  Recent,  Mediterranean  Sea. 

The  following  is  a  description  of  the  genus  Spondylus : 

Shell  reaching  a  large  size,  trigonal-suborbicular;  auricles  small,  sub¬ 
equal;  right  valve  higher  and  more  inflated  than  left;  sculpture  consisting 
of  low  radial  ribs  and  foliaceous  lamellae  or  spines;  cardinal  area  wider  on 
right  valve  than  on  left;  chondrophore  small,  triangular,  median;  hinge 
of  both  valves  consisting  of  2  heavy  crural  teeth,  representing  laterals,  and 
2  sockets  symmetrically  placed  with  respect  to  chondrophore;  right  valve 
bearing  along  lower  outer  edge  of  cardinal  area  on  both  sides  a  rude 
horizontal  lamella  fitting  into  space  between  crural  tooth  and  lower  margin 
of  cardinal  area  of  left  valve;  muscular  impression  suborbicular,  posterior. 

Spondylus  has  a  long  geologic  history.  Its  present  distribution  in 
the  warm  seas  of  the  world  is  similar  to  its  Tertiary  distribution. 

Key  to  the  Bowden  species  of  Spondylus. 

Spine-bearing  ribs  widely  spaced,  spines  short .  S.  bostrychites 

Spine-bearing  ribs  closely  spaced,  spines  long . S.  species 


76 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Spondylus  bostrychites  Guppy. 

(Plate  9,  Figures  5  to  7.) 

Spondylus  bifrons  Sowerby,  1849,  Quar.  Jour.  Geol.  Soc.  London,  vol.  6,  p.  53. 
Not  S.  bifrons  Goldfuss,  1835. 

Spondylus  bostrychites  Guppy  (part),  1867,  Proc.  Sci.  Assoc.  Trinidad,  pt.  3, 
p.  176.  Guppy,  1873,  Proc.  Sci.  Assoc.  Trinidad,  vol.  2,  No.  2,  p.  87. 
Gabb,  1873,  Trans.  Am.  Philos.  Soc.,  n.  s.,  p.  257.  Guppy  (part),  1874, 
Geol.  Mag.,  decade  2,  vol.  1,  p.  443  (list).  Dali  (part),  1898,  Trans. 
Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  pp.  758-759.  Maury, 
1917,  Bull.  Am.  Paleontology,  vol.  5,  pp.  354-355,  plate  58,  fig.  4.  ?  Maury, 

1920,  Sci.  Survey  Porto  Rico  and  Virgin  Islands,  vol.  3,  part  1,  pp.  22-23, 
N.  Y.  Acad.  Sci.  ?  Hubbard,  1921,  Sci.  Survey  Porto  Rico  and  Virgin 
Islands,  vol.  3,  part  2,  p.  97,  N.  Y.  Acad.  Sci.  Pilsbry,  1922,  Proc.  Acad. 
Nat.  Sci.  Philadelphia,  vol.  73,  p.  413.  Not  Dali,  1915,  U.  S.  Nat.  Mus. 
Bull.  90,  p.  124,  plate  19,  fig.  4.  Not  Cooke,  1919,  Carnegie  Inst.  Wash. 
Pub.  291,  p.  144,  plate  11,  figs.  11  a,  b. 

The  following  is  the  original  description  of  this  species: 

Testa  subregularis,  rotondata,  ventricosa,  margine  latiusulco,  valide 
denticulate;  extus  radiatim  costata,  costa  5  ad  6  spiniferis;  area  cardinali 
alterius  valvae  angustissima,  alterius  latiori. 

Type  locality. — Dominican  Republic. 

The  following  is  a  description  of  Bowden  specimens  of  this  species: 

Shell  medium-sized,  suborbicular,  auricles  moderately  large;  right  valve 
much  more  inflated  than  left  and  bearing  a  much  wider  cardinal  area; 
sculpture  of  right  valve  consisting  of  8  to  10  low  primary  radial  ribs  from 
which  short  spines,  which  usually  are  broken,  rise  at  irregular  intervals; 
between  primary  ribs  are  4  to  5  secondary  ribs  of  irregular  width ;  near  the 
base  the  secondaries  are  almost  or  quite  as  high  as  primaries;  all  ribs  and 
interspaces  near  base  sculptured  with  looped  concentric  lamellae  and  fine 
scales  arranged  in  linear  radial  series;  left  valve  sculptured  with  lower 
and  narrower  ribs,  the  ribs  and  interspaces  bearing  radial  rows  of  fine 
scales,  like  on  right  valve;  cardinal  area  of  right  valve  very  wide,  almost 
horizontal;  cardinal  area  of  left  valve  very  narrow,  virtually  vertical. 

Length  47  mm.;  height  52  mm.;  diameter  (right  valve)  15  mm.;  length 
of  hinge  27  mm. 

The  name  Spondylus  bostrychites  has  been  applied  to  specimens 
from  the  Dominican  Republic,  Jamaica,  Anguilla,  Antigua,  Porto 
Rico,  and  Florida,  collected  from  beds  of  middle  Oligocene  to  middle 
Miocene  age.  These  specimens  probably  represent  2  or  3  species. 
The  first  step  is  to  consider  the  type  of  S.  bostrychites.  The  type  of 
this  species  is  the  same  as  the  type  of  S.  bifrons  Sowerby  in  the 
British  Museum.  The  fossils  that  Sowerby  described  came  from  the 
Yaque  Valley,  Dominican  Republic,  and  as  virtually  all  the  species 
have  been  discovered  in  the  Gurabo  formation,  it  can  safely  be 
assumed  that  the  common  Spondylus  in  the  Gurabo  formation  is  S. 
bostrychites .  When  Guppy  renamed  S.  bifrons  Sowerby  he  stated 
that  the  species  is  found  in  “Haiti”  and  Anguilla  and  2  shells  from 
Anguilla  in  the  Guppy  collection  (U.  S.  Nat.  Mus.  No.  115523)  are 


PELECYPODS. 


77 


labeled  “types.”  But  2  shells  from  Bowden  in  the  Guppy  collection 
(U.  S.  Nat.  Mus.  No.  115522)  also  are  labeled  “types.”  Guppy’s 
designation  of  these  specimens  in  his  collection  as  types  has  no  bear¬ 
ing  whatever  on  the  actual  type  of  S.  bostrychites. 

Specimens  of  S.  bostrychites  from  the  Gurabo  formation  are  more 
than  100  mm.  in  length  and  height  and  have  relatively  wide  and 
widely  spaced  primary  ribs.  Specimens  from  Bowden  seem  to  repre¬ 
sent  this  species,  but  there  are  no  perfect  large  shells.  A  broken  piece 
in  the  United  States  National  Museum  collection  (No.  135773)  is 
part  of  a  large  valve  comparable  in  size  to  the  Dominican  valves.  It 
has  wider  ribs  and  larger  scales  than  specimens  from  the  Gurabo 
formation.  Plate  9,  figures  5  and  6,  represent  a  much  smaller  right 
valve  having  an  abnormally  thick  umbo.  These  small  shells  from 
Bowden  have  slightly  larger  auricles  than  small  shells  from  the 
Gurabo  formation  and  the  rows  of  scales  are  farther  apart.  Some 
left  valves  from  the  Gurabo  formation  are  as  inflated  as  right  valves, 
but  this  feature  is  variable.  Additional  material  may  show  that  the 
Bowden  Spondylus  represents  a  different  species,  though  in  essential 
features  it  resembles  S.  bostrychites. 

Shells  from  Anguilla  and  Antigua  have  more  numerous  and  usually 
narrower  ribs  bearing  spines.  The  valves  that  are  in  attached  position 
seem  to  have  a  more  symmetrical  cardinal  area,  but  this  feature  may 
be  due  to  position  during  growth. 

A  right  valve  from  the  Tampa  formation  is  more  elongate  and  has 
many  narrow  ribs  of  uniform  width.  S.  chipolanus  Dali  also  has 
many  narrow  ribs  bearing  long  spines. 

Other  localities. — Gurabo  formation  (middle  Miocene),  Dominican 
Republic. 

Type  material. — 6  cotypes  (Geol.  Soc.  London  No.  12833),  depos¬ 
ited  in  British  Museum  (Natural  History),  Geological  Department. 

Spondylus  species. 

(Plate  9,  Figure  8.) 

The  following  is  a  description  of  this  species: 

Shell  small,  higher  than  wide;  valve  sculptured  with  11  or  12  ribs, 
bearing  closely  spaced  spines  that  are  very  long  for  the  size  of  the  shell 
and  slightly  curved;  on  parts  of  the  shell  the  spines  are  represented  by 
irregularly  curled  lamellae  extending  across  one  or  more  ribs;  between  the 
primary  ribs  are  poorly  defined  radial  rows  of  small,  irregularly  spaced 
scales,  interrupted  by  the  transgression  of  the  broad  scales;  auricles  small, 
their  surface  roughened  or  bearing  a  few  spines;  inner  surface  of  the  valve 
irregularly  fluted;  left  valve  not  known. 

Length  10  mm.;  height  11.8  mm.;  diameter  3  mm.;  length  of  hinge 
5.5  mm. 

This  species  is  known  only  from  a  small  right  valve.  It  is  remark¬ 
ably  similar  to  the  living  West  Indian  species  S.  echinatus  (Martyn), 


78 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


which  has  not  been  recorded  from  deposits  older  than  Pleistocene. 
No  Recent  shells  comparable  in  size  are  available  for  comparison. 
The  spines  of  the  shell  that  generally  has  been  called  S.  spathuliferus 
are  more  compressed  dorso-ventrally,  and  their  ends  are  irregularly 
fluted,  but  apparently  the  spinose  sculpture  is  variable,  as  is  indicated 
by  the  elaborate  synonomy  given  by  Dali. 

Genus  PLICATULA  Lamarck. 

Lamarck,  1801,  Systeme  des  Animaux  sans  Vertebres,  p.  152 

Type  (by  subsequent  designation,  Gray,  184-7.) — Plicatula  gibbosa 
Lamarck.  Recent,  West  Indies. 

The  following  is  a  description  of  the  genus  Plicatula : 

Shell  small,  irregular  in  outline,  attached  by  either  valve;  sculpture  con¬ 
sisting  of  broad  radial  ribs  that  may  divide  near  margin;  cardinal  area 
very  small;  chondrophore  narrow,  elongate,  flanked  on  each  side  by  a  fluted 
crural  tooth  representing  a  lateral,  and  socket;  impression  of  adductor 
muscle  ovate,  posterior;  margin  of  valve  fluted. 

The  present  distribution  of  Plicatula  in  some  of  the  warm  seas 
(West  Indies,  Pacific  and  Indian  Oceans)  is  more  restricted  than  its 
Tertiary  distribution. 

Plicatula  guppyi,  new  species. 

(Plate  9,  Figures  9  to  11.) 

Plicatula  vexillata  Guppy  (part),  1873,  Proc.  Sci.  Assoc.  Trinidad,  vol.  2,  No. 
2,  pp.  86-87  (not  plate  2,  fig.  7,  =  P.  gibbosa  Lamarck).  Guppy  (part), 
1874,  Geol.  Mag.,  decade  2,  vol.  1,  p.  436  (not  plate  17,  fig.  7,  =  P.  gibbosa 
Lamarck) . 

Plicatula  densata  Dali  (part,  not  Conrad),  1898,  Trans.  Wagner  Free  Inst. 
Sci.  Philadelphia,  vol.  3,  part  4,  p.  763. 

The  following  is  a  description  of  this  species: 

Shell  small,  subequilateral  or  very  inequilaterial,  moderately  or  slightly 
inflated,  outline  irregular,  usually  more  or  less  rounded-triangular  or  sub- 
ovate;  umbos  low;  sculpture  consisting  of  5  to  9  strong  ribs,  most  prom¬ 
inent  at  ventral  margin  and  not  extending  to  umbo;  concentric  sculpture 
consisting  of  irregular,  more  or  less  overlapping  lamellae,  stronger  on  the 
ribs  and  in  some  shells  producing  short,  broad  scales  on  the  ribs;  inner 
margin  of  valve  coarsely  fluted  by  the  ribs  and  usually  finely  corrugated; 
inner  surface  of  valve  irregular. 

Right  valve:  length  12  mm.;  height  15.5  mm.;  diameter  2.8  mm. 

The  type  material  of  P.  vexillata  consists  of  2  cotypes.  One,  an 
entire  shell,  was  the  specimen  figured  and  described  by  Guppy.  It 
seems  to  be  a  small  P.  gibbosa  Lamarck,  as  it  has  the  color  markings 
and  other  features,  as  Dali  has  shown.  It  does  not  have  the  yellowish- 
brown  color  of  shells  from  Bowden  and  probably  is  a  Quaternary 
shell  mixed  in  Guppy’s  collection  with  Bowden  shells.  The  other 
specimen,  which  has  the  appearance  of  a  Bowden  shell,  is  a  smaller 
right  valve.  It  is  the  holotype  of  P.  guppyi .  Other  specimens  of  P. 
guppyi  are  in  all  collections  examined. 


PELECYPODS. 


79 


P.  guppyi  is  smaller  than  P.  gibbosa,  and  has  more  distinctly 
foliaceous  ribs.  It  also  is  smaller  than  P.  densata  Conrad,  an  Ameri¬ 
can  Miocene  species,  and  has  more  distinctly  foliaceous  ribs  and  no 
secondary  marginal  ribs.  Probably  the  same  species  has  been 
recorded  by  Olsson  from  Miocene  beds  in  Panama  and  Costa  Rica 
under  the  name  of  Plicatula  marginata  Say.1  All  specimens  from 
Bowden,  and  apparently  those  from  Panama  and  Costa  Rica,  are 
smaller  than  P.  marginata,  an  American  upper  Miocene  and  Pliocene 
species,  and  consequently  have  narrower  and  lower  ribs. 

Type  material. — Holotype  (a  right  valve  in  the  Guppy  collection, 
1  of  the  2  cotypes  of  P.  vexillata,  U.  S.  Nat.  Mus.  No.  115536). 

Family  LIMIDAE. 

Genus  LIMA  Cuvier. 

Subgenus  LIMA  s.  s. 

Section  LIMA  s.  s. 

Cuvier,  1798,  Tableau  Elementaire  de  l’Histoire  Naturelle  des  Animaux,  p.  421. 

Type  (by  monotypy). — Ostrea  lima  Linne.  Recent,  Indo-Pacific. 

The  following  is  a  description  of  the  section  Lima  s.  s.: 

Shell  medium-sized,  moderately  inflated,  obliquely  inequilateral,  anterior 
submargin  flattened;  anterior  and  posterior  ends  narrowly  gaping;  auricles 
unequal,  the  posterior  larger;  sculpture  consisting  of  scaly  ribs;  cardinal 
area  wide,  triangular,  chondrophore  large,  central;  hinge  edentulous;  ad¬ 
ductor  scar  high,  posterior;  margin  of  valve  fluted. 

The  Tertiary  and  present  distribution  of  Lima  is  almost  cosmo¬ 
politan. 

Lima  (Lima)  stenacostata,  new  species. 

(Plate  9,  Figures  12,  13.) 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  moderately  inflated,  very  inequilateral  and  oblique; 
sculpture  consisting  of  24  low  narrow  ribs,  separated  by  broader  inter¬ 
spaces;  the  ribs  are  widest  and  most  prominent  in  the  umbonal  region, 
toward  the  ventral  margin  they  become  higher  and  may  have  short  nar¬ 
row  scales  at  irregular  intervals,  or  are  roughened  by  irregular  incremental 
lamellae  on  the  lower  third  of  the  shell;  anterior  submargin  wide,  long, 
deeply  depressed;  posterior  submargin  much  smaller  and  less  deeply  de¬ 
pressed;  auricles  small,  subequal,  not  differentiated  from  submargins; 
both  auricles  and  submargins  sculptured  with  irregular  concentric  lamellae 
and  indistinct  radials;  cardinal  area  wide;  ligament  pit  large,  deep,  sub- 
umbonal  and  vertical,  extending  into  cavity  of  shell;  ventral  margin  of 
valve  scarcely  affected  by  ribs. 

Length  10.5  mm.;  height  12  mm.;  diameter  (left  valve)  ,2.8  mm.;  length 
of  hinge  5  mm. 

The  preceding  description  is  based  on  the  holotype,  a  left  valve, 
which  is  the  only  specimen.  The  radial  sculpture  is  weaker  than  in 


1  Comparison  based  on  figures. 


80 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


most  species  of  the  section  Lima  s.  s.  The  posterior  submargin  is 
unusually  long  and  so  deeply  depressed  that  it  has  a  decided  effect  on 
the  outline  of  the  shell.  L.  tampaensis  Dali,  described  from  the 
Chipola  formation  of  Hillsborough  Bay,  Florida,  is  larger  and  has 
stronger  radials  and  a  fluted  base. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352792). 

Section  MANTELLUM  Bolten. 

Bolten,  1798,  Museum  Boltenianum,  part  2,  p.  160. 

Type  (by  subsequent  designation,  Bucquoy,  Dautzenberg,  and 
Dollfus,  1888). — Ostrea  inflata  Gmelin.  Recent.  Mediterranean  Sea. 

The  following  is  a  description  of  the  section  Mantellum : 

Shell  medium-sized,  thin;  strongly  inflated,  obliquely  inequilateral, 
posterior  and  anterior  ends  widely  gaping;  auricles  small,  subequal; 
sculpture  consisting  of  narrow  radial  ribs,  roughened  by  incremental ; 
cardinal  area  narrow;  chondrophore  very  large;  part  of  shell  under  cardinal 
area  excavated  on  posterior  side;  hinge  edentulous;  ventral  margin  of 
valve  weakly  fluted. 

The  greater  inflation,  wider  gape,  absence  of  flattened  anterior 
submargin,  and  weak  sculpture  separate  Mantellum  from  Lima  s.  s. 
Ostrea  hians  Gmelin,  a  species  that  is  not  in  Bolten’s  original  list, 
usually  is  cited  as  the  type  of  Mantellum. 

The  Tertiary  and  living  species  of  Mantellum  have  a  wide  distri¬ 
bution. 

Lima  (Mantellum)  species. 

(Plate  9,  Figures  14,  15.) 

The  following  is  a  description  of  this  species: 

Shell  small,  fragile,  obliquely  elongate,  dorsal  margins  short,  straight, 
the  anterior  longer;  posterior  end  rounded  above,  slightly  insinuated  at 
dorsal  margin  of  gape,  obliquely  truncated  below;  anterior  margin  sub¬ 
parallel  to  posterior  truncation;  base  rounded;  sculpture  consisting  of  a 
few  barely  visible  narrow  ribs  near  the  ventral  margin,  extending  almost 
half  the  length  of  shell  in  posterior-ventral  region;  concentric  sculpture 
limited  to  a  few  weak,  fine  lamellae  on  ventral  half  of  shell;  entire  surface 
covered  with  microscopic  vermicular  markings,  most  prominent  on  umbo; 
cardinal  area  narrow;  chondrophore  wide,  shallow,  not  projecting  into 
cavity  of  shell ;  interior  of  valve  bearing  faint  radial  markings  in  posterior- 
ventral  region. 

Median  length  (measured  along  a  line  perpendicular  to  the  oblique 
axis)  5  mm.;  height  7  mm.;  diameter  (right  valve)  1.8  mm.;  length  of 
hinge  1.5  mm. 

The  very  oblique  outline  and  almost  smooth  surface  of  this  species, 
which  is  represented  by  a  broken  right  valve,  are  characteristic  fea¬ 
tures. 


PELECYPODS. 


81 


Genus  LIMEA  Bronn. 

Bronn,  1831,  Italiens  Tertiar-Gebilde  undj  deren  organische  Einschliisse, 
p.  115. 

Type  (by  monotypy). — Ostrea  strigilata  Brocchi.  Miocene  and 
Pliocene,  Italy. 

The  following  is  a  description  of  the  genus  Limea: 

Shell  very  small,  obliquely  subovate,  strongly  inflated;  auricles  small, 
subequal;  sculpture  consisting  of  minutely  beaded  radial  ribs;  cardinal  area 
narrow;  chondrophore  small,  triangular,  subumbonal;  hinge  consisting  of  a 
series  of  taxodont  denticulations  on  both  sides  of  chondrophore;  margin 
of  valve  fluted. 

This  little  genus  has  an  unusual  geologic  history.  In  Europe  it  is 
recorded  from  deposits  of  Jurassic  age.  One  of  these  European 
species,  L.  duplicata  Sowerby,  has  been  described  from  Jurassic  beds 
in  east  Greenland,  but  there  are  no  other  American  Mesozoic  species. 
No  fossil  species  are  known  from  the  American  mainland  north  of 
Central  America.  The  Bowden  species  here  described  is  the  only 
American  Tertiary  species.  It  has  recently  been  discovered  in  Mio¬ 
cene  beds  in  Costa  Rica  and  the  Domincan  Republic.  The  few  living 
species  are  confined  to  the  seas  of  Europe,  the  Atlantic  Ocean,  and 
the  West  Indies. 

Limea  solida  Dali. 

(Plate  10,  Figures  1,  2.) 

Limea  solida  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3, 
part  4,  p.  769,  plate  35,  figs.  4,  5.  Olsson,  1922,  Bull.  Amer.  Paleontology, 
vol.  9,  p.  381,  plate  31,  fig.  10. 

The  following  is  the  original  description  of  this  species: 

Shell  minute,  solid,  rounded  triangular,  with  about  12  rounded,  strong, 
slightly  granular  radial  ribs,  separated  by  narrower  interspaces  crossed  by 
lines  of  growth;  submargins  without  radial  sculpture;  hinge-line  short,  with 
a  small  central  pit,  on  each  side  of  which  are  about  8  teeth ;  interior  radially 
feebly  grooved,  the  basal  margin  crenulated  by  the  ribs;  shell  moderately 
inflated.  Alt.  3.5,  lat.  3.3,  diam.  2.5  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  subovate-trigonal,  strongly  inflated  in  umbonal  region,  sub- 
equilateral;  curve  of  the  lower  part  of  posterior  margin  slightly  more  con¬ 
vex  than  corresponding  part  of  anterior  margin;  base  gently  arcuate;  umbos 
prominent;  sculpture  consisting  of  14  to  16  strong  radial  ribs  that  are 
rounded  on  immature  shells,  but  on  adults  are  angular  on  the  lower  third 
of  their  length  and  bear  minute  beads  on  their  sides;  ribs  separated  by 
interspaces  of  virtually  the  same  width;  each  interspace  bearing  a  small, 
median,  rounded,  minutely  beaded  ridge;  submargins  sculptured  with  10 
to  15  concentric  rugae,  the  posterior  submargin  longer  and  usually  having 
more  prominent  and  more  numerous  rugae;  chondrophore  small,  shallow, 
subumbonal,  flanked  by  6  to  8  teeth  on  either  side;  inner  margin  of  part 


82 


MTOCENE  MOLLUSKS  FROM  BOWDEN. 


of  shell  that  has  radial  sculpture  deeply  fluted;  interior  of  shell  bearing 
inconspicuous  radial  undulations  corresponding  to  external  radial  sculpture. 

Length  3  mm.;  height  3.2  mm.;  diameter  (left  valve)  0.9  mm. 

One  of  the  valves  shows  traces  of  dark  coloration.  Two  valves  of 
apparently  the  same  species,  though  slightly  smaller  than  the  largest 
Bowden  shells,  were  collected  from  the  Gurabo  formation  in  the 
Dominican  Republic  at  station  8544  on  Rio  Gurabo.  Olsson  records 
a  small  specimen  having  only  12  ribs  from  Costa  Rica. 

Other  localities. — Gurabo  formation  (middle  Miocene),  Dominican 
Republic.  Gatun  formation  (middle  Miocene),  Costa  Rica. 

Type  material. — Holotype  (left  valve)  (U.  S.  Nat.  Mus.  No. 
135679). 

Superfamily  ANOMIACEA. 

Family  ANOMIIDAE. 

Genus  PLACUN AN OMIA  Broderip. 

Broderip,  in  Broderip  and  Sowerby,  1832,  Proceedings  Zoological  Society  of 
London,  part  2,  p.  28. 

Type  (by  monotypy) . — Placunanomia  cumingii  Broderip.  Recent, 
Pacific  coast  of  Central  America. 

The  following  is  a  description  of  the  genus  Placunanomia: 

Shell  large,  suborbicular,  irregularly  warped;  surface  smooth  or  weakly 
sculptured;  umbo  of  right  valve  bearing  closed  byssal  opening;  right 
valve  bearing  2  strong  cardinal  crura  that  diverge  at  an  acute  angle  and  fit 
into  a  wide  triangular  depression  on  the  left  valve;  outer  edge  of  crura 
fitting  into  crude  sockets  along  edge  of  triangular  depression;  margin  of 
valve  roughened  on  both  sides  of  crura;  adductor  scar  submedian,  byssal 
scar  lying  obliquely  above  it  and  smaller. 

Placunanomia  is  restricted  to  the  Pacific  Ocean,  but  is  one  of  many 
genera  that  formerly  lived  in  Atlantic  waters,  where  it  was  repre¬ 
sented  by  P.  plicata  Tuomey  and  Holmes,  from  the  Duplin  marl  of 
the  Carolinas,  and  P.  lithobleta  Dali,  a  middle  Miocene  West  Indian 
and  Central  American  species.  According  to  Tuomey  and  Holmes,  a 
living  P.  plicata  was  obtained  from  Charleston  Harbor,  but  this  record 
is  discredited  by  Dali. 


Placunanomia  lithobleta  Dali. 

(Plate  10,  Figures  3  to  5.) 

Placunanomia  lithobleta  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  4,  pp.  778-779.  Maury,  1917,  Bull.  Amer.  Paleon¬ 
tology,  vol.  5,  p.  356,  plate  60,  figs.  1,  2.  Olsson,  1922,  Bull.  Amer. 
Paleontology,  vol.  9,  p.  382,  plate  24,  figs.  3  to  5. 

The  following  is  the  original  description  of  this  species: 

Shell  resembling  P.  plicata  [Tuomey  and  Holmes],  but  flatter;  not 
plicate,  but  gently  waved  distally;  surface  radially  sculptured  with 
minute,  almost  microscopic,  threads,  which  are  frequently  interrupted, 
when  the  termination  of  the  proximal  part  of  the  thread  is  swollen,  resem- 


PELECYPODS. 


83 


bling  a  minute  head  or  pustule;  interior  resembling  P.  plicata,  but  the  hinge 
weaker,  the  amorphous  irregularities  confined  to  a  very  small  space  near 
the  umbo,  and  inconspicuous;  crura  of  the  lower  valve  small,  forming  an 
acute  angle,  well  elevated,  the  socket  for  their  reception  on  the  opposite 
valve  shallow.  Alt.  about  50,  lat.  50,  diam.  about  8  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  large,  compressed,  irregularly  suborbicular;  irregularly  warped  and 
folded,  the  broad  undulations  most  pronounced  at  the  ventral  margin,  but 
not  definitely  plicate;  umbonal  region  of  some  shells  swollen;  sculpture 
consisting  of  fine,  discontinuous  swollen  radial  threads,  broken  up  into 
longer  or  shorter  parts,  or  interrupted  so  frequently  that  they  produce  a 
finely  pustulose  appearance;  byssal  plug  on  right  valve  elongate,  triangular, 
extending  almost  to  cardinal  margin;  internal  cardinal  “rugosities”  obscure 
or  absent;  right  valve  bearing  strong  cardinal  crura,  diverging  at  an  acute 
angle;  left  valve  bearing  a  large  triangular  umbonal  depression  into  which 
the  crura  of  the  right  valve  are  received,  the  anterior  and  posterior  outer 
part  of  the  depression  separated  by  a  triangular  elevated  area  correspond¬ 
ing  to  the  depressed  area  between  the  crura  on  the  right  valve. 

All  the  valves  of  this  species  are  more  or  less  broken.  The  largest 
is  about  48  mm.  in  length  and  height.  The  radial  sculpture  is  irregu¬ 
lar.  Some  parts  of  the  shell,  especially  the  umbonal  region,  may  be 
smooth,  or  the  fine,  swollen  radial  threads  may  cover  the  entire 
surface.  On  one  left  valve  the  radials  are  well  developed.  Another 
left  valve,  of  which  only  the  dorsal  half  is  preserved,  has  only  very 
faint  concentric  markings  and  the  triangular  hinge  depression  does 
not  have  a  median  lower  raised  area. 

As  stated  in  the  original  description,  P.  lithobleta  may  be  recog¬ 
nized  by  its  radial  sculpture.  P.  plicata  Tuomey  and  Holmes  is  a 
smooth,  marginally  plicate  species  confined  to  the  Duplin  marl  of 
the  Carolinas.  Maury  has  recorded  P.  lithobleta  from  an  unknown 
Miocene  horizon  in  the  Dominican  Republic,  and  Olsson  has  recorded 
it  from  Miocene  beds  in  Costa  Rica. 

Other  localities. — Middle  (?)  Miocene,  Dominican  Republic. 
Gatun  formation  (middle  Miocene),  Costa  Rica. 

Type  material. — 2  cotypes  (U.  S.  Nat.  Mus.  No.  135778). 

Genus  ANOMIA  Linne. 

Linne,  1758,  Systema  Naturae,  ed.  10,  p.  700. 

Type  (by  subsequent  description,  Gray  181+7). — Anomia  ephippium 
Linne.  Recent,  seas  of  Europe. 

The  following  is  a  description  of  the  genus  Anomia: 

Shell  medium-sized,  thin,  irregular  in  outline,  attached  by  left  valve, 
which  is  more  convex  than  right;  exterior  smooth,  or  more  or  less  lamellar; 
resilium  attached  to  umbonal  cavity  of  left  valve  and  to  dorsal  margin 
of  right;  interior  of  left  valve  bearing  a  subcentral  group  of  3  muscle-scars, 
the  upper  scar,  which  is  the  scar  of  the  upper  byssal  muscle,  the  largest,  the 


84 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


other  2  scars  lower,  the  anterior  one  being  the  lower  byssal  scar,  the  poster¬ 
ior  one  the  adductor  scar;  right  valve  perforated  by  the  byssal  foramen,  the 
interior  bearing  only  the  adductor  scar. 

The  Tertiary  and  present  distribution  of  Anomia  is  cosmopolitan. 

Anomia  indecisa  Dali. 

(Plate  10,  Figures  6  to  9.) 

Anomia  simplex  Guppy  and  Dali  (not  d’Orbigny),  1896,  U.  S.  Nat.  Mus. 
Proc.,  vol.  19,  p.  326.  Maury  (not  d’Orbigny),  1917,  Bull.  Amer.  Paleon¬ 
tology,  vol.  5,  p.  355,  plate  26,  fig.  15. 

Anomia  microgrammata  var.  indecisa  (Guppy  Mss.)  Dali,  1898,  Trans. 
Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  p.  783. 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  suborbicular;  left  valve  moderately  inflated,  right 
valve  flat;  external  surface  smooth,  or  bearing  very  fine  obscure  radial 
threads  near  the  ventral  margin;  upper  byssal  scar  on  left  valve  large, 
lower  byssal  scar  and  adductor  scar  very  small,  far  below  the  upper  byssal 
scar,  placed  on  a  slightly  oblique  line. 

Left  valve:  length  19  mm.;  height  18.5  mm.;  diameter  5  mm. 

Type  locality. — Bowden,  Jamaica. 

A.  indecisa  resembles  A.  microgrammata  Dali,  which  is  confined  to 
the  Chipola  formation  of  Florida,  but  the  sculpture  is  more  obscure 
and  the  lower  byssal  and  adductor  scars  are  much  smaller  and  farther 
from  the  upper  byssal  scar.  Externally  the  Bowden  species  more 
closely  resembles  the  living  West  Indian  A.  simplex  d’Orbigny,  but 
the  lower  byssal  and  adductor  scars  are  smaller,  farther  from  the 
upper  byssal  scar,  and  more  nearly  in  the  same  horizontal  plane. 

Specimens  from  the  Cercado  formation  in  the  Dominican  Republic 
have  the  same  kind  of  muscle-scars,  but  the  umbo  of  the  left  valve  is 
more  inflated.  Fragments  of  probably  the  same  species  were  collected 
from  the  Gurabo  formation."  The  Miocene  species  recorded  by  Olsson 
from  Panama  and  Costa  Rica  is  larger,  but  its  muscle-scars  have  not 
been  described. 

All  the  cotypes  of  A.  indecisa  have  glue  on  some  of  the  muscle-scars. 

Other  localities. — Cercado  formation  (lower  Miocene),  Dominican 
Republic.  (?)  Gurabo  formation  (middle  Miocene),  Dominican 
Republic. 

Type  Material. — 4  cotypes  (U.  S.  Nat.  Mus.  No.  107107). 

Superfamily  MYTILACEA. 

Family  MYTILIDAE. 

Genus  MODIOLUS  Lamarck. 

Section  MODIOLUS  s.  s. 

Lamarck,  1799,  Memoires  de  la  Societe  d’Histoire  Naturelle  de  P&ris, 
pp.  87,  88. 

Type  (by  monotypy). — Mytilus  modiolus  Linne.  Recent,  seas  of 
Europe. 


PELECYPODS. 


85 


The  following  is  a  description  of  the  section  Modiolus  s.  s. 

Shell  medium-sized,  moderately  inflated,  transversely  elongate;  umbos 
not  terminal;  external  surface  smooth  except  for  incrementals;  ligament 
subinternal;  hinge  edentulous;  anterior  adductor  scar  near  umbo,  posterior 
scar  large. 

Modiolus  s.  s.  is  not  represented  in  the  fauna  of  the  Bowden  forma¬ 
tion. 


Section  BRACHYDONTES  Swainson. 

Swainson,  1840,  A  Treatise  on  Malacology,  p.  384. 

Type  (by  monotypy). — Modiola  sulcata  Lamarck.  Recent,  Indian 
Ocean. 

The  following  is  a  description  of  the  section  Brachydontes : 

Shell  resembling  Modiolus  s.  s.  in  outline;  sculpture  consisting  of  narrow 
radial  ribs;  cardinal  border  slightly  corrugated;  ventral  and  posterior 
margin  of  valve  finely  corrugated. 

The  Tertiary  and  living  species  of  Brachydontes  are  most  abundant 
in  tropical  waters.  During  Tertiary  time  they  were  more  widely  dis¬ 
tributed  than  at  the  present  time. 

Modiolus  (Brachydontes)  guppyi  Dali. 

(Plate  10,  Figures  10  to  12.) 

Modiolus  ( Brachydontes )  gwp-pyi  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  4,  p.  794,  plate  35,  fig.  16. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  thin,  delicate,  radially  numerously  ribbed,  the  ribs  but 
seldom  dichotomous,  general  form  as  in  M.  grammatus  [Dali] ,  but  shorter 
and  more  rounded,  the  surface  frequently  concentrically  faintly  undulated, 
inner  dorsal  margin  sharply  crenulate,  the  rest  of  the  shell  margin  almost 
smooth,  basal  end  of  the  valve  rounded,  dorsal  angle  obsolete.  Alt.  8.5, 
max.  lat.,  4.7,  diam.,  2.5  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  thin,  transversely  elongate,  widest  at  about  middle  of  shell; 
umbos  inflated,  almost  terminal;  umbonal  ridge  strong,  rounded,  becoming 
lower  and  broader  toward  posterior  end;  inner  third  or  more  of  dorsal 
margin  straight,  forming  a  subrounded  angle  of  about  140°  with  the  outer 
part,  which  is  gently  curved  or  slightly  emarginate ;  ventral  margin  usually 
slightly  concave;  posterior  margin  narrow,  abruptly  rounded;  sculpture 
consisting  of  numerous  inconspicuous  rounded  ribs,  separated  by  interspaces 
of  the  same  width  or  narrower;  ribs  usually  absent  on  the  most  convex  part 
of  the  umbonal  ridge;  concentric  sculpture  consisting  of  usually  faint  in¬ 
cremental  threads,  occasionally  exaggerated;  hinge  bearing  2  or  3  projec¬ 
tions  on  left  valve  and  obscure  sockets  on  right;  inner  part  of  inner  dorsal 
margin  conspicuously  corrugated,  the  outer  part  weakly  corrugated,  re¬ 
mainder  of  the  margin  usually  smooth  or  faintly  corrugated. 

Length  10.5  mm.;  height  5.5  mm.;  diameter  1.8  mm. 


86 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  height  varies,  the  measured  valve  being  the  highest.  All  the 
shells  have  a  rudimentary  hinge.  One  of  the  left  valves  has  3  small 
distinct  projections,  and  most  of  the  others  have  suggestions  of  2  or  3 
similar  projections.  Right  valves  have  corresponding  obscure  depres¬ 
sions. 

The  differences  between  this  species  and  M.  grammatus  Dali,  de¬ 
scribed  from  the  Tampa  formation  of  Florida,  are  given  by  Dali  in 
the  original  description.  The  living  West  Indian  species  M.  citrinus 
Bolten  is  larger,  wider,  more  rounded  anteriorly,  and  its  entire  inner 
margin  is  corrugated. 

Type  material. — 2  cotypes  (U.  S.  Nat.  Mus.  No.  135747). 

Family  DREISSENIDAE. 

Genus  MYTILOPSIS  Conrad. 

Conrad,  1857,  Proceedings  Academy  of  Natural  Sciences  of  Philadelphia, 
p.  167. 

Type  (by  monotypy). — Mytilus  leucophyaetus  Conrad.  Recent, 
southeastern  United  States. 

The  following  is  a  description  of  the  genus  Mytilopsis: 

Shell  small,  strongly  inflated,  mytiloid,  slightly  gaping  along  anterior 
part  of  ventral  margin;  surface  smooth,  except  for  incrementals ;  ligament 
subinternal;  hinge  edentulous;  anterior  adductor  seated  on  a  short  septum 
that  roofs  over  the  umbonal  cavity,  the  septum  prolonged  downward  on 
the  dorsal  side  into  a  short  pointed  apophysis,  extending  toward  the  um¬ 
bonal  cavity;  byssal  muscle  attached  to  apophysis;  posterior  adductor 
scar  long,  bilobed. 

Mytilopsis  has  been  confused  with  the  genus  Congeria  Partsch. 
The  type  of  Congeria,  C.  subglobosa  Partsch,  has  a  large,  heavy  sub¬ 
quadrate  shell  that  has  strongly  incurved  umbos.  The  attachment 
of  the  anterior  adductor  and  byssal  muscles  is  similar  in  the  two 
genera,  but  the  septum  of  Congeria  is  much  heavier  and  wider  and 
the  apophysis  is  not  directed  downward  into  the  umbonal  cavity.  The 
posterior  adductor  scar  of  Congeria  has  the  outline  of  the  figure  6. 

In  general  features,  Mytilopsis  resembles  Dreissena  Vanbeneden 
(type,  Mytilus  polymorphus  Pallas)  more  closely  than  Congeria,  but 
the  septum  of  Dreissena  is  simple  and  lacks  the  apophysis.  Mytilopsis 
seems  to  be  the  American  representative  of  Congeria. 

Mytilopsis  jamaicensis,  new  species. 

(Plate  10,  Figures  13,  14.) 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  strongly  inflated,  mytiloid,  slightly  gaping  along 
ventral  margin  near  anterior  end;  dorsal  margin  subangular  or  abruptly 
convex;  umbonal  ridge  rounded,  lying  close  to  ventral  margin;  sculpture 
limited  to  irregularly  spaced,  occasionally  exaggerated  incrementals;  septum 
short,  shallow;  apophysis  rounded,  projecting  far  into  umbonal  cavity. 

Length  18  mm.;  height  9.5  mm.;  diameter  (left  valve)  3  mm. 


PELECYPODS. 


87 


M.  jamaicensis  closely  resembles  the  common  Mytilopsis  from  Colon 
that  is  known  as  M.  cocheata  (Kickx),  but  the  septum  of  the  Bowden 
species  is  narrower;  the  apophysis  more  rounded;  and  the  area  of 
attachment  of  the  byssal  muscle  smaller.  M.  rossmassleri  (Dunker), 
a  living  West  Indian  species,  has  a  longer  septum  and  more  pointed 
apophysis.  The  outline  of  all  these  species  is  similar.  Authentic 
specimens  of  M.  doming ensis  (Recluz),  which  was  described  from  the 
island  of  Haiti,  are  not  available  for  comparison.  Maury  has  reported 
M.  domingensis  from  the  Cercado  formation  of  the  Dominican  Re¬ 
public.  The  Bowden  species  has  a  narrower  and  shallower  septum 
than  M.  lamellata  (Dali),  described  from  the  Pliocene  Caloosahatchee 
marl  of  Florida,  and  the  shell  is  not  so  high. 

Type  material. — Holotype  (left  valve)  (U.  S.  Nat.  Mus.  No. 
352795). 

Family  JULIIDAE. 

Genus  JULIA  Gould. 

Gould,  1862,  Proceedings  Boston  Society  of  Natural  History,  vol.  8,  p.  284. 

Type  (by  monotypy)  —Julia  exquisita  Gould.  Recent,  Hawaiian 
Islands. 

The  following  is  a  description  of  the  genus  Julia : 

Shell  small,  moderately  inflated,  subquadrate;  umbos  terminal,  proso- 
gyrate;  lunule  small,  deeply  depressed,  indenting  margin  of  shell;  margin  of 
shell  projecting  outward  below  lunule;  sculpture  limited  to  incrementals ; 
ligament  subinternal;  hinge  edentulous;  edge  of  lunule  of  right  valve 
thickened  and  fitting  behind  a  similar  thickening  on  left  valve;  anterior 
adductor  scar  small,  orbicular,  subcentral. 

This  curious  genus  has  an  interesting  present  and  past  distribution. 
At  the  present  time  it  is  confined  to  the  Hawaiian  Islands  and  the 
island  of  Bourbon  or  Reunion  east  of  Madagascar.  Only  4  fossil 
species,  all  of  Miocene  age,  have  been  described.  As  they  occur  in 
southeastern  United  States  and  in  southern  France,  the  genus  had  a 
more  extensive  Miocene  distribution.  Julia  floridana  Dali,  the  only 
American  species  heretofore  described,  is  confined  to  the  Chipola  for¬ 
mation  of  Florida.  The  following  3  European  species  have  been 
described:  J.  girondica  (Benoist),  from  the  Aquitanian  of  Aquitaine; 
J.  douvillei  Cossmann  and  Peyrot,  from  beds  probably  of  Helvetian 
age  in  Aquitaine;  J.  lecointreae  Dollfus  and  Dautzenberg,  from  the 
Helvetian  of  Touraine.  An  undescribed  species  was  collected  by  the 
U.  S.  Geological  Survey  expedition  from  the  Cercado  and  Gurabo 
formations  of  the  Dominican  Republic. 


88 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Julia  gardnerae,  new  species. 

(Plate  10,  Figures  15,  16.) 

The  following  is  a  description  of  this  species: 

Shell  small,  subquadrate,  moderately  inflated;  dorsal  margin  arcuate; 
posterior  margin  rounded;  base  sloping  toward  posterior  end;  umbo  prom¬ 
inent,  placed  at  anterior  end,  strongly  bent  downward  over  the  narrow 
deeply  impressed  lunule,  margin  below  lunule  sloping  downward  to  the 
prominently  extended  anterior-ventral  angle;  at  the  anterior  end  a  sub¬ 
rounded  ridge  curves  from  the  umbo  to  the  extended  angle;  inner  edge  of 
lunule  of  right  valve  flattened  and  extended,  margin  below  lunule  extended 
outward  by  the  thickened  ventral  edge  of  the  lunule;  inner  edge  of  lunule 
of  left  valve  thickened;  muscle-scar  obscure. 

Length  8  mm.;  height  6.5  mm.;  diameter  (left  valve)  2.2  mm. 

This  species  is  described  from  a  number  of  valves,  of  which  2  are 
adult.  It  resembles  J.  floridana  Dali,  but  is  larger,  heavier,  more 
elongate,  and  has  fuller  umbos,  deeper  lunule,  and  the  inner  edge  of 
the  lunule  is  more  heavily  thickened.  The  undescribed  species  from 
the  Dominican  Republic  is  as  large  as  J.  gardnerae ,  but  in  general 
features  closely  resembles  J.  floridana.  All  these  American  species 
are  larger  than  the  type  of  the  genus,  but  none  has  the  inner  edge  of 
the  lunule  so  heavily  thickened  and  extending  so  far  toward  the 
interior  of  the  shell.  J.  gardnerae  resembles  J.  douvillei  more  closely 
than  the  other  European  species. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352796). 

Superfamily  POROMYACEA. 

Family  POROMYACIDAE. 

Genus  POROMYA  Forbes. 

Forbes,  1844,  Report  British  Association  for  Advancement  of  Science  for  1843, 
p.  143. 

Type  (by  monotypy) . — Poromya  anatinoides  Forbes  (=  Corbula 
granulata  Nyst  and  Westendorp).  Tertiary  and  Recent,  Mediter¬ 
ranean  Sea. 

The  following  is  a  description  of  the  genus  Poromya: 

Shell  small,  ovate,  subequilateral ;  umbos  full,  central,  prosogyrate; 
sculpture  consisting  of  fine  granules  arranged  in  radial  series;  hinge  of 
right  valve  consisting  of  a  strong  subumbonal  cardinal  tooth  in  front  of  a 
wide  chondrophore ;  hinge  of  left  valve  consisting  of  a  small  cardinal  tooth 
behind  and  above  the  chondrophore. 

There  are  only  a  few  Tertiary  and  living  species  of  Poromya.  The 
living  species,  some  of  which  are  deep-water  dwellers,  have  a  restricted 
distribution  around  the  borders  of  the  Atlantic  and  Pacific. 

Poromya  jamaicensis  Dali. 

(Plate  10,  Figures  17  to  19.) 

Poromya  jamaicensis  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia, 
vol.  3,  part  6,  p.  1509,  plate  56,  fig.  23. 


PELECYPODS. 


89 


The  following  is  the  original  description  of  this  species: 

Shell  small;  hinge,  interior  and  surface  sculpture  like  those  of  P.  granu- 
lata  Nyst  [and  Westendorpl  but  differing  from  it  by  the  absence  of  rostra- 
tion  at  the  posterior  end,  which  is  evenly  rounded  though  more  attenuated 
than  the  anterior  end.  Length  5.5,  height  4.7,  diameter  3.0  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  subequilateral,  posterior  end  more  extended,  compressed 
toward  posterior  end;  posterior  part  of  base  slightly  emarginate  on  valves 
that  have  a  decided  posterior  extension;  area  in  front  of  umbo  slightly 
excavated;  sculpture  consisting  of  conspicuous  granules,  obscurely  arranged 
in  radial  series,  the  granules  finer  toward  posterior  end;  ligament  area 
opisthodetic,  narrow,  flattened,  extending  along  entire  posterior  dorsal 
margin,  poorly  defined  on  left  valve;  chondrophore  conspicuous,  placed 
behind  umbo,  directed  toward  posterior  end,  almost  external  on  left  valve; 
hinge  of  right  valve  consisting  of  a  heavy  cardinal  in  front  of  the  chondro¬ 
phore;  hinge  of  left  valve  consisting  of  an  obscure  cardinal  between  the 
chondrophore  and  socket  for  right  cardinal;  anterior  dorsal  margins  bent 
upward  near  umbo,  left  posterior  dorsal  margin  extended;  interior  sub- 
nacreous. 

Length  7.5  mm.;  height  6.5  mm.;  diameter  (left  valve)  2.5  mm. 

The  posterior  end  of  some  valves  is  slightly  extended  and  rounded ; 
on  others  it  is  more  extended  and  obscurely  truncate.  Most  valves 
that  have  a  rounded  posterior  end  are  right  valves,  and  they  have 
lower  and  broader  umbos.  The  granules  may  be  arranged  along  radial 
lines,  but  this  arrangement  is  obscure  or  even  absent  on  some  shells. 
The  living  West  Indian  species  that  is  called  P.  granulata  is  larger, 
more  elongate  and  has  finer  granules. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135690). 

Family  CUSPID  ARIIDAE. 

Genus  CUSPID  ARIA  Nardo. 

Subgenus  CUSPIDARIA  s.  s. 

Nardo,  1840,  Revue  Zoologique,  par  la  Societe  Cuvierienne,  Annee  1840, 
p.  30. 

Type  {by  monotypy). — Tellina  cuspidata  Olivi.  Recent,  Mediter¬ 
ranean  Sea. 

The  following  is  a  description  of  the  subgenus  Cuspidaria  s.  s. : 

Shell  medium-sized,  rostrate,  left  valve  a  little  larger  and  more  inflated 
than  right;  umbos  inflated,  prosogyrate;  sculpture  consisting  of  exaggerated 
incrementals ;  both  valves  bear  a  long,  narrow,  obliquely  curved  chondro¬ 
phore;  right  valve  bearing  a  long,  wide  upturned  posterior  lateral;  pallial 
sinus  shallow,  wide. 

Cuspidaria  s.  s.  is  represented  in  most  of  the  present  seas.  Some  of 
the  species  live  in  deep  water.  There  are  no  species  in  the  Bowden 
formation. 


90 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Subgenus  CARDIOMYA  A.  Adams. 

A.  Adams,  1864,  Annals  and  Magazine  of  Natural  History,  ser.  3,  vol.  13, 
p.  330. 

Type  (by  monotypy) . — Neaera  gouldiana  Hinds.  Recent,  seas  of 
Japan.1 

According  to  Dali,  Cardiomya  resembles  Cuspidaria  s.  s.,  but  has 
radial  sculpture,  and  a  more  vertical  and  prominent  chondrophore. 

The  present  distribution  of  Cardiomya  is  less  extensive  than  its 
Tertiary  distribution. 

Cuspidaria  (Cardiomya)  craspedonia  Dali. 

(Plate  10,  Figures  20  to  22.) 

?  Neaera  costellata  Guppy  (not  Deshayes),  1866,  Quart.  Jour.  Geol.  Soc. 
London,  vol.  22,  p.  575  (name  only).  Guppy  (not  Deshayes),  1873, 
Proc.  Sci.  Assoc.  Trinidad,  vol.  2,  No.  2,  p,  85  (name  only). 

Cuspidaria  ( Cardiomya )  craspedonia  Dali,  1903,  Trans.  Wagner  Free  Inst. 
Sci.  Philadelphia,  vol.  3,  part  6,  p.  1506,  plate  57,  fig.  17. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  plump,  rostrate,  the  disk  sculptured  with  numerous  elevated, 
simple,  radial  threads,  with,  in  the  interspaces,  from  1  to  3  much  finer 
subequal  threads,  the  whole  crossed  by  fine  concentric  lines  of  growth; 
the  major  radials  increase  somewhat  in  prominence  near  the  posterior  end; 
beaks  low,  submedian,  inconspicuous;  rostrum  small,  short,  slightly  re¬ 
curved,  subtruncate  terminally,  sculptured  concentrically  with  a  single 
feeble  thread  extending  from  the  beaks  to  the  lower  posterior  extremity; 
hinge  normal,  fossette  very  small;  interior  basal  margin  fringed  by  small 
projections  corresponding  to  the  major  radial  sculpture.  Length  4.0, 
height  2.5,  diam.  2.0  mm. 

Type  locality. — Bowden,  Jamaica. 

The  chondrophore  is  small  and  almost  vertical.  The  left  anterior 
dorsal  margin  is  extended  and  slightly  bent  upward. 

C.  craspedonia  is  smaller  than  C.  islahispaniolae  Maury,  which  was 
described  from  the  Cercado  formation  of  the  Dominican  Republic, 
and  has  stronger  and  less  numerous  radial  threads.  It  also  resembles 
C.  ornatior  Pilsbry  and  Johnson,  one  of  Gabb’s  species  from  an 
unknown  horizon  in  the  Dominican  Republic,  but  has  a  shorter  pos¬ 
terior  snout,  and  narrower  and  higher  ribs. 

Type  material. — 3  cotypes  (U.  S.  Nat.  Mus.  No.  135691). 

Subgenus  BOWDENIA  Dali. 

Dali,  1903,  Transactions  Wagner  Free  Institute  of  Science  of  Philadelphia, 
vol.  3,  part  6,  p.  1504. 

Type  (by  original  designation). — Cuspidaria  (Bowdenia)  distira 
Dali.  Miocene,  Jamaica. 

The  following  is  a  description  of  the  subgenus  Bowdenia: 

Shell  small,  rostrate;  umbos  strongly  inflated,  prosogyrate;  sculpture  con¬ 
sisting  of  fine  radial  threads;  hinge  of  right  valve  consisting  of  a  prominent 


1 1  have  not  seen  the  type  species. 


PELECYPODS. 


91 


posterior  cardinal  tooth  behind  the  small  shallow  chondrophore,  margin  of 
■valve  behind  chondrophore  slightly  thickened;  dorsal  margin  of  right 
valve  grooved  near  posterior  end;  hinge  of  left  valve  consisting  of  an 
obscure  posterior  lateral  behind  the  subumbonal  chondrophore;  dorsal 
margin  of  left  valve  abruptly  arched  behind  chondrophore  to  receive  right 
posterior  cardinal. 

Bowdenia  resembles  Cardiomya  in  external  features,  but  has  a  dif¬ 
ferent  hinge.  The  type  is  the  only  known  species. 

Cuspidaria  (Bowdenia)  distira  Dali. 

(Plate  11,  Figures  1  to  5.) 

Cuspidaria  ( Bowdenia )  distira  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  6,  p.  1506,  plate  57,  fig.  16. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  plump,  with  elevated  beaks  nearly  centrally  situated,  atten¬ 
uated,  rostrate,  and  compressed  behind;  sculptured  with  2  strong  threads, 
one  on  the  anterior  dorsal  slope  and  the  other  near  the  posterior  border  of 
the  disk,  which  by  its  projection  angulates  the  basal  margin;  between  these 
two  the  surface  is  finely,  radially  striate,  and  a  few  nearly  obsolete  stria- 
tions  occur  behind  the  posterior  thread;  rostrum  compressed,  straight  or 
a  little  decurved,  nearly  smooth,  a  few  faint  radial  striae  on  its  basal  aspect, 
rounded  terminally;  hinge  as  described  in  the  diagnosis  of  the  subgenus; 
basal  margin  entire  except  where  the  radial  thread  forms  a  small  projection. 
Length  3,  height  2,  diameter  2  mm. 

Type  locality. — Bowden,  Jamaica. 

This  small  Cuspidaria  seems  to  be  unlike  any  other  described 
species. 

Type  material.— 3  cotypes  (U.  S.  Nat.  Mus.  No.  135692). 

Family  VERTICORDIIDAE. 

Genus  VERTICORDIA  J.  Sowerby. 

Subgenus  VERTICORDIA  s.  s. 

J.  Sowerby,  1844,  Mineral  Conchology  of  Great  Britain,  vol.  7,  plate  639. 

Type  (by  monotypy) . — V erticordia  cardiiformis  J.  Sowerby.  Plio¬ 
cene,  England. 

The  following  is  a  description  of  the  subgenus  V erticordia  s.  s.: 

Shell  small,  cardiform,  nacreous;  umbos  strongly  prosogyrate;  lunule 
deeply  depressed;  sculpture  consisting  of  high,  narrow  radial  ribs  roughened 
by  concentric  beads;  ligament  internal;  right  valve  bearing  a  heavy  sub¬ 
umbonal  tooth;  inner  edge  of  lunule  on  left  valve  thickened;  ventral  margin 
of  valve  deeply  fluted. 

V erticordia  s.  s.  is  represented  by  living  species  in  many  parts  of 
the  world.  The  oldest  species  are  of  Eocene  age.  There  are  no 
Bowden  species. 


92 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Subgenus  TRIGONULINA  d’Orbigny. 

d’Orbigny,  1853,  in  de  la  Sagra,  Histoire  Physique,  Politique  et  Naturelle 
de  1’  He  de  Cuba;  Mollusques,  voi.  2,  p.  291.  (Spanish  edition  1845?). 

Type  {by  monotypy). — Trigonulina  ornata  d’Orbigny.  Recent, 
West  Indies. 

The  following  is  a  description  of  the  subgenus  Trigonulina: 

Shell  small,  cardiform,  nacreous,  strongly  inflated;  umbos  flattened, 
strongly  prosogyrate;  lunule  very  deeply  depressed;  sculpture  consisting  of 
a  few  high,  narrow  radial  ribs,  interspaces  a.t  the  posterior  end  of  shell 
very  wide;  ligament  internal;  ligament  groove  long  and  deep  on  right 
valve;  hinge  like  in  V erticordia  s.  s. 

V erticordia  s.  s.  and  Trigonulina  are  very  similar.  They  differ  in 
sculpture  and  Trigonulina  has  a  more  deeply  depressed  lunule  and 
deeper  ligament  groove.  Trigonulinas  are  characteristic  of  the  West 
Indies  and  nearby  regions.  Species  of  Eocene,  Oligocene,  and  Miocene 
age  have  been  described  from  the  Gulf  states. 

Verticordia  (Trigonulina)  bowdenensis  Dali. 

(Plate  11,  Figures  6  to  8.) 

Verticordia  ( Trigonulina )  bowdenensis  Dali,  1903,  Trans.  Wagner  Free  Inst. 
Sci.  Philadelphia,  vol.  3,  part  6,  p.  1512. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  rotund,  rather  convex,  with  8  or  9  anterior  radial  ribs  with 
deep,  subequal  interspaces,  then  a  wide  space  followed  by  2  adjacent  ribs, 
then  a  much  wider  space  with  another  adjacent  pair  beyond  it  separated 
by  a  smooth  area,  larger  in  the  left  than  in  the  right  valve,  from  the  poste¬ 
rior  margin;  the  surface  when  intact  is  covered  with  minute  granules  ar¬ 
ranged  in  rows  harmonizing  with  the  ribs;  lunule  very  deeply  impressed 
in  the  left  valve,  less  so  in  the  right;  tooth  of  the  right  valve  large  and 
strong,  the  posterior  margin  of  the  left  valve  modified  to  form  a  lamina  or 
lateral  tooth  received  in  a  groove  of  the  opposite  valves.  Lon.  2.7,  alt.  2.6, 
diam.  2.0  mm. 

Type  locality. — Bowden,  Jamaica. 

The  largest  valve  has  the  following  dimensions:  length  3.5  mm.; 
height  3.5  mm.;  diameter  (right  valve)  1.5  mm.  Dali  has  noted  that 
this  species  was  labeled  “V.  ornata  d’Orbigny/’  the  type  of  the  sub¬ 
genus,  in  the  Guppy  collection.  The  Bowden  species  has  more  numer¬ 
ous  and  narrower  ribs  and  narrower  interspaces,  but  the  interspace  at 
the  posterior  end  of  the  shell  is  relatively  wider. 

Type  material. — 3  cotypes  (U.  S.  Nat.  Mus.  No.  135689). 

Subgenus  HALIRIS  Dali. 

Dali,  1866,  Bulletin  Museum  of  Comparative  Zoology  at  Harvard  College, 
vol.  12,  p.  287. 

Type  {by  original  designation ). — Verticordia  fischeriana  Dali. 
Recent,  Gulf  of  Mexico. 


PELECYPODS. 


93 


The  following  is  a  description  of  the  subgenus  Haliris: 

Shell  small,  cardiform,  nacreous,  strongly  inflated;  umbos  full,  strongly 
prosogyrate;  lunule  moderately  depressed;  sculpture  consisting  of  narrow 
radial  ribs,  ribs  and  interspaces  granulated;  hinge  of  left  valve  consisting  of 
an  obscure  subumbonal  cardinal;  hinge  of  right  valve  consisting  of  a  large 
subumbonal  cardinal  fitting  in  front  of  left  cardinal;  ventral  margin  of 
valve  fluted. 

The  hinge  and  sculpture  of  Haliris  are  its  most  conspicuous  fea¬ 
tures.  Haliris  is  an  American  group  of  Verticordias  dating  back  to 
Eocene  time. 

Verticordia  (Haliris)  jamaicensis  Dali. 

(Plate  11,  Figures  9  to  11.) 

Verticordia  ( Haliris )  jamaicensis  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  6,  p.  1511. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  thin,  subquadrate,  inflated,  with  strongly  prosocoelus  beaks; 
sculptured  with  about  27  radial  close-set  ribs  with  narrower  interspaces;  a 
smooth,  deep  lunar  impression  in  front  of,  and  a  narrow,  escutcheon-like 
smooth  area  behind  them,  the  whole  surface  minutely  granulose;  basal 
margin  angularly  produced  near  the  middle,  internally  minutely  fluted  in 
harmony  with  ribs;  hinge  normal;  Alt.  4.75,  long.  4.5,  diam.  4.6  mm. 

Type  locality. — Bowden,  Jamaica. 

One  of  the  broken  valves  of  this  species  that  is  much  larger  than 
the  cotypes  has  the  following  dimensions:  length  12.5  mm.;  height 
12  mm.;  diameter  5.5  mm.  Adult  shells  have  less  conspicuous  mar¬ 
ginal  fluting  and  the  basal  angle  is  more  or  less  straightened. 

V.  jamaicensis  resembles  in  general  features  the  type  of  the  sub¬ 
genus,  V.  fischeriana  Dali,  but  is  smaller  and  has  a  more  angular  base 
and  flatter  umbos. 

Type  material.-— 3  cotypes  (U.  S.  Nat.  Mus.  No.  135688). 

Superfamily  ASTARTACEA. 

Family  CRASSATELLITIDAE. 

Genus  CRASSATELLITES  Krueger. 

Subgenus  CRASSATELLITES  s.  s. 

Krueger,  1823,  Geschichte  der  Urwelt,  part  2,  p.  466. 

Type. — Crassatellites  sinuatus  Krueger  ( =Crassatella  gibbosula 
Lamarck).  Eocene,  Paris  Basin.1 

The  following  is  a  description  of  the  subgenus  Crassatellites  s.  s.: 

Shell  heavy,  medium-sized  or  large,  subquadrate  or  subtrigonal,  inequi¬ 
lateral;  umbos  low,  rounded;  lunule  and  escutcheon  depressed;  sculpture 
consisting  of  concentric  lamellae  or  rugae;  cardinal  area  wide;  ligament 
and  resilium  internal,  adjacent,  seated  on  a  large  deep  subumbonal 
chondrophore ;  hinge  of  right  valve  consisting  of  3  cardinals,  the  anterior 


The  description  is  based  on  Crassatella  gibbosula  Lamarck. 


94  MIOCENE  MOLLUSKS  FROM  BOWDEN. 

(3a)1  and  middle  (1)  ones  fused  and  diverging  at  an  acute  angle,  the 
posterior  one  (36)  reduced  to  a  ridge  along  lower  edge  of  chondrophore; 
hinge  of  left  valve  consisting  of  2  cardinals  (2a  and  26)  separated  by  a 
wide,  deep  socket,  the  posterior  one  forming  a  ridge  along  anterior  edge  of 
chondrophore;  right  valve  bearing  an  obscure  anterior  and  posterior  lateral; 
left  valve  bearing  a  long  posterior  lateral  and  a  less  distinct  anterior 
lateral;  adductor  scars  deeply  depressed;  inner  margin  of  valve  finely  cor¬ 
rugated. 

Many  of  the  American  Tertiary  species  are  more  elongate  and  more 
rostrate  than  the  type  species,  and  have  no  vestige  of  a  right  posterior 
cardinal  (36)  and  no  corrugations  on  the  inner  margin  of  the  valve. 
Dali  has  placed  these  species  in  the  section  Scambula.  The  name 
Scambula  was  proposed  by  Conrad2  for  an  Upper  Cretaceous  species, 
S.  perplana  Conrad,  from  New  Jersey.  This  species  has  also  been 
found  in  Upper  Cretaceous  deposits  in  Georgia  and  Tennessee.  It  is 
very  small,  unusually  flat,  has  a  different  hinge,  and  in  general  fea¬ 
tures  resembles  Crassinella.  The  name  Scambula  can  be  used  only 
for  this  peculiar  Upper  Cretaceous  shell.  The  difference  between  the 
Bowden  species,  which  belong  to  the  group  that  has  been  called 
Scambula ,  and  the  type  of  Crassatellites  hardly  warrants  a  new 
section  name. 

The  living  species  of  Crassatellites,  also  known  as  Crassatella,  are 
restricted  to  the  warm  seas.  It  formerly  had  a  more  extensive  distri¬ 
bution  in  the  northern  hemisphere,  where  it  was  conspicuous  in 
virtually  all  Eocene,  Oligocene,  and  Miocene  faunas. 

Key  to  the  Bowden  species  of  Crassatellites  s.  s. 


Posterior  dorsal  margin  slightly  excavated .  C.  ( C .)  jamaicensis 

Posterior  dorsal  margin  deeply  excavated .  C.  (C.)  altaspissus 


Crassatellites  (Crassatellites)  jamaicensis  Dali. 

(Plate  11,  Figures  12  to  15.) 

Crassatellites  ( Scambula )  jamaicensis  Dali,  1903,  Trans.  Wagner  Free  Inst. 

Sci.  Philadelphia,  vol.  3,  part  6,  pp.  1471-1472,  plate  49,  fig.  13. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  nearly  equilateral,  subtrigonal,  rounded  below  and  in  front 
with  posterior  end  obliquely  subtruneate  and  a  feeble  carina  bounding  the 
posterior  dorsal  area;  lunule  and  escutcheon  subequal,  moderately  im¬ 
pressed;  nepionic  shell  flattened,  with  7  or  8  concentric  low  undulations, 
which  extend  down  about  one-fourth  of  the  way  to  the  basal  margin 
mesially,  and  on  the  anterior  slope  are  continuous,  though  the  greater  part 
of  the  disk  and  the  whole  of  the  posterior  dorsal  area  are  smooth  except  for 
incremental  lines;  hinge  normal,  the  posterior  right  cardinal  nearly  oblit¬ 
erated;  laminar  grooves  deep;  internal  margins  of  the  valves  smooth. 
Lon.  49,  alt.  37,  diam.  20  mm. 

Type  locality. — Bowden,  Jamaica. 

1  The  symbols  in  parenthesis  refer  to  the  notation  for  cardinal  teeth  originally  used  by  Bernard 
and  Munier-Chalmas.  Many  of  the  notations  are  adapted  from  Cossmann  and  Peyrot. 

*  T.  A.  Conrad.  Amer.  Jour.  Conch.,  vol.  5,  p.  48.  1869. 


PELECYPODS. 


95 


The  shell  is  slightly  depressed  in  front  of  the  posterior  ridge,  but 
not  enough  to  affect  the  margin.  Between  the  ridge  and  the  escutch¬ 
eon  lies  a  fainter  ridge;  midway  between  the  two  ridges  is  a  faint 
shallow  groove  on  the  ventral  half  of  the  shell.  The  relative  width 
of  the  lunule  and  escutcheon  is  variable,  but  they  are  subequal  in 
length  and  the  lunule  usually  is  more  deeply  depressed.  On  the 
largest  valve  the  concentric  undulations  are  somewhat  irregular  on 
the  ventral  half  of  the  anterior  slope.  The  middle  cardinal  (1)  on 
the  right  valve  is  very  small. 

Dali  has  described  a  similar  species  from  the  Chipola  formation — 
C.  chipolanus.  It  has  fine  concentric  undulations  on  the  entire  sur¬ 
face,  except  on  the  posterior  slope.  On  some  shells  the  concentric 
sculpture  may  disappear  or  may  be  present  on  only  the  anterior  third 
or  less  of  the  shell.  Such  shells  differ  from  C.  jamaicensis  by  having 
from  2  to  4  very  coarse  undulations  a  short  distance  from  the  tip  of 
the  umbo,  which  may  be  smooth  or  feebly  undulated;  and  the  undula¬ 
tions  down  the  anterior  slope,  if  present,  are  finer  than  those  on  the 
Bowden  species ;  in  addition  the  umbos  are  slightly  lower ;  the  lunule 
narrower,  and  the  hinge  not  so  heavy. 

Specimens  of  this  species  in  Guppy’s  collections  were  labeled  “C. 
marylandicus  Conrad,”  but  that  species  is  very  different. 

Type  material. — 4  cotypes  (U.  S.  Nat.  Mus.  No.  135683). 

r 

Crassatellites  (Crassatellites)  altaspissus,  new  species. 

(Plate  11,  Figures  16,  17.) 

The  following  is  a  description  of  this  species : 

Shell  medium-sized,  heavy,  moderately  inequilateral;  posterior  margin 
obliquely  truncated,  base  slightly  emarginate  in  front  of  posterior  ridge; 
umbos  high,  incurved,  the  apex  flattened;  escutcheon  slightly  wider  and 
longer  than  lunule,  both  moderately  depressed;  posterior  ridge  low;  a 
lower  and  broader  ridge  extends  from  the  umbo  to  the  upper  edge  of  the 
posterior  truncation;  sculpture  consisting  of  9  concentric  undulations  in 
the  umbonal  region,  the  ventral  few  slightly  crowded;  on  the  anterior  slope 
finer  concentric  undulations  extend  almost  half  of  distance  from  umbo  to 
ventral  margin,  remainder  of  shell  smooth  except  for  incrementals ;  hinge 
high,  massive,  the  right  posterior  cardinal  (36)  absent;  inner  margin  of 
valve  smooth. 

Length  61  mm.;  height  45  mm.;  diameter  (right  valve)  18  mm. 

This  species,  which  is  based  on  an  adult  right  valve  and  a  young 
right  valve,  closely  resembles  C.  densus  Dali,  described  from  the  Oak 
Grove  sand  of  Florida,  but  is  proportionally  higher,  more  convex  and 
has  a  more  excavated  posterior  dorsal  margin,  longer  posterior  trun¬ 
cation,  and  more  numerous  and  finer  umbonal  concentric  undulations. 
The  undulations  on  the  anterior  slope  of  C.  altaspissus  are  coarser, 
but  the  change  from  one  series  to  the  other  is  not  abrupt  as  on  C. 
densus.  C.  altaspissus  is  distinguished  from  C.  jamaicensis  by  its 
more  elongate  outline,  more  excavated  posterior  dorsal  margin,  and  by 


96 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


the  presence  of  concentric  undulations  on  only  the  upper  half  or  less  of 
the  anterior  slope.  It  has  essentially  the  same  outline  as  the  Miocene 
species  from  Panama  and  Costa  Rica  called  C.  reevei  by  Olsson,  but 
does  not  have  concentric  rugae  on  the  anterior  part  of  the  shell. 

Type  material. — Ilolotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352797). 

Genus  CRASSINELLA  Guppy. 

Guppy,  1874,  Geological  Magazine,  decade  2,  vol.  1,  p.  442;  1875,  Geological 
Magazine,  decade  2,  vol.  2,  p.  42. 

Type. — Thetis  parva  C.  B.  Adams  (?= Crassatella  martinicensis 
d’Orbigny).  Recent,  West  Indies. 

The  following  is  a  description  of  the  genus  Crassinella: 

Shell  small,  flattened,  rounded  triangular,  slightly  inequilateral;  posterior 
dorsal  margin  excavated;  lunule  and  escutcheon  flattened;  umbos  acute; 
sculpture  consisting  of  concentric  lamellae;  cardinal  area  narrow;  ligament 
and  resilium  internal;  chondrophore  small;  hinge  consisting  of  2  cardinals 
in  each  valve;  cardinals  of  left  valve  (2a  and  25)  separated  by  chondro¬ 
phore,  cardinals  of  right  valve  (3a  and  1)  lying  in  front  of  chondrophore; 
right  valve  bearing  an  anterior  lateral,  and  left  valve  a  posterior  lateral; 
on  the  left  valve  a  low  median  ridge  separates  the  chondrophore  from  the 
socket  in  front  of  it;  inner  margin  of  valve  smooth. 

As  Crassinella  was  proposed  to  replace  the  preoccupied  name 
Gouldia  C.  B.  Adams,1  which  C.  B.  Adams  had  used  for  the  preoccu¬ 
pied  name  Thetis  C.  B.  Adams,2  it  is  necessary  to  use  as  the  type  one 
of  the  species  originally  included  under  the  name  Thetis.  Adams 
listed  2  new  species,  Thetis  cerina  and  Thetis  parva,  both  from 
Jamaica.  Thetis  parva  is  herewith  designated  the  type.  It  closely 
resembles  and  may  be  identical  with  Crassatella  martinicensis 
d’Orbigny. 

These  small  bivalves,  also  known  as  Crassitina,  are  abundant  in 
the  Tertiary  faunas  of  Europe  and  America.  They  are  living  in  the 
tropical  and  temperate  waters  of  the  Atlantic. 

Key  to  the  Bowden  species  of  Crassinella . 

Posterior  dorsal  margin  excavated,  sculpture  consisting  of  widely  spaced, 

sharp-crested  lamellae .  C.  guppyi 

Posterior  dorsal  margin  not  excavated. 

Shell  slightly  inflated;  sculpture  consisting  of  crowded,  irregularly  spaced 

rugae  or  lamellae .  C.  bowdenensis 

Shell  strongly  inflated;  sculpture  consisting  of  regularly  spaced  rugae .  C.  xena 

Crassinella  guppyi  (Dali). 

Plate  11,  Figures  18  to  20.) 

Crassatellites  ( Crassinella )  Guppyi  Dali,  in  Guppy  and  Dali,  1896,  Proc. 
U.  S.  Nat.  Mus.,  vol.  19,  p.  326,  plate  30,  fig.  5.  Dali,  1903,  Trans. 
Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  6,  p.  1476. 

Not  Crassinella  guppyi  Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5,  p.  361, 
plate  52,  fig.  21. 

1  C.  B.  Adams.  Catalogue  of  the  genera  and  species  of  recent  shells  in  the  collection  of  C.  B. 
Adams,  p.  29  (footnote).  1847. 

*  C.  B.  Adams.  Proc.  Boston  Soc.  Nat.  Hist.,  vol.  2,  p.  9.  1845. 


PELECYPODS. 


97 


The  following  is  the  original  description  of  this  species: 

Rounded  trigonal,  flattish,  concentrically  costate,  with  10  to  12  lamellar 
ribs,  much  narrower  than  the  interstices.  Alt.  4.6,  Ion.  4.6  mm. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  compressed  or  slightly  inflated,  outline  irregularly  rounded- 
triangular,  moderately  inequilateral ;  posterior  dorsal  margin  usually 
slightly  longer  than  anterior  and  excavated,  especially  on  right  valve, 
meeting  ventral  margin  at  a  sharp  or  subrounded  angle;  anterior  dorsal 
margin  straighter  or  slightly  convex,  rounding  into  the  asymmetrically 
arcuate  base;  umbos  relatively  high,  acute  and  compressed;  escutcheon 
usually  wider  and  more  deeply  flattened  than  lunule;  sculpture  of  adult 
valve  consisting  of  8  to  16  sharp-crested  concentric  lamellae,  which  are 
crowded  and  occasionally  interrupted  near  ventral  margin. 

Length  4.8  mm.;  height  4.5  mm.;  diameter  (right  valve)  1  mm. 

The  largest  valve  has  the  following  dimensions:  length  6  mm.; 
height  5.6  mm.;  diameter  (right  valve)  1.2  mm.  This  species  re¬ 
sembles  the  living  West  Indian  C.  guadalupensis  d’Orbigny,  but  is 
smaller,  more  inflated  and  has  lower  umbos  and  less  regularly  spaced 
concentric  lamellae.  The  same  differences  separate  it  from  C.  lunu- 
latus  (Conrad),  a  Miocene  and  Pliocene  species  from  the  Middle 
Atlantic  States.  The  dorsal  margin  of  C.  acutus  Dali,  which  was 
described  from  Pliocene  beds  in  Florida,  met  at  a  more  acute  angle. 
The  species  listed  by  Guppy  as  C.  martinicensis  d’Orbigny  from 
Matura,  Trinidad,  has  rounded  concentric  lamellae. 

C.  guppyi  is  larger  than  the  species  described  by  Maury  as  “C. 
guppyi”  from  the  Cercado  formation  of  the  Dominican  Republic,  and 
has  more  deeply  excavated  posterior  dorsal  slopes  and  coarser  sculp¬ 
ture.  Apparently  the  same  species  as  Maury’s  “C.  guppyi ”  was  col¬ 
lected  from  the  Gurabo  formation  by  the  U.  S.  Geological  Survey 
party.  C.  guppyi  radiata  Pilsbry,  a  subspecies  from  an  unknown 
Miocene  horizon  in  the  Dominican  Republic,  has  fine  radial  striae. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No, 
107151). 

Crassinella  bowdenensis  (Dali). 

(Plate  12,  Figures  1  to  4.) 

Crassatellites  ( Crassinella )  bowdenensis  Dali,  1903,  Trans.  Wagner  Free  Inst. 

Sci.  Philadelphia,  vol.  3,  part  6,  p.  1476,  plate  50,  figs.  2,  3. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  thick  and  solid,  plump,  subequilateral,  the  anterior  side  a 
little  shorter,  beaks  small,  acute,  recurved;  lunule  and  escutcheon  lance¬ 
olate,  subequal,  well  impressed,  smooth;  valves  with  subequal  dorsal  slopes 
and  prominently  arcuate  base,  sculptured  with  concentric,  close-set, 


98 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


flattened  threads,  which  near  the  umbos  are  less  crowded  and  slightly 
sharper;  hinge  solid,  strong,  normal.  Height,  3.5,  length,  3.7,  diameter 
2.0  mm. 

Type  locality. — Bowden,  Jamaica. 

Some  shells  are  almost  equilateral  and  their  sculpture  consists  of 
fine  concentric  rugae.  On  other  shells  the  posterior  dorsal  margin  is 
slightly  concave  and  the  umbo  is  not  so  full.  The  sculpture  may 
resolve  itself  into  rather  widely  spaced  sharp  lamellae,  thus  approach¬ 
ing  the  sculpture  of  C.  guppyi,  though  not  so  coarse. 

C.  bowdenensis  is  more  convex  and  more  triangular  than  C.  bow- 
denensis  costaricensis  Olsson,  a  Miocene  Costa  Rican  subspecies. 
C.  bowdenensis  resembles  C.  triangulatus  Dali,  a  Chipola  marl  spe¬ 
cies,  but  is  more  inflated,  and  has  stronger  and  more  regular  sculpture. 
It  is  larger  and  more  inflated  than  C.  martinicensis  (d’Orbigny),  the 
living  West  Indian  species,  and  has  less  uniform  sculpture. 

Type  material. — 4  cotypes  (U.  S.  Nat.  Mus.  No.  135685). 

Crassinella  xena,  new  species. 

(Plate  12,  Figures  5,  6.) 

The  following  is  a  description  of  this  species: 

Shell  small,  high,  slightly  inequilateral,  obliquely  rounded-triangular; 
posterior  dorsal  margin  longer,  slightly  convex;  umbos  full,  acute,  de¬ 
cidedly  opisthogyrate ;  escutcheon  slightly  broader  and  shorter  than  lunule, 
both  moderately  flattened;  adult  shell  sculptured  with  15  to  18  prominent, 
evenly  spaced  rounded  rugae,  separated  by  narrower  interspaces. 

Length  2.8  mm.;  height  2.6  mm.;  diameter  (left  valve)  0.9  mm. 

This  species  resembles  C.  microdelta  (Pilsbry  and  Johnson),  which 
was  collected  by  the  U.  S.  Geological  Survey  expedition  from  the 
Cercado  formation  on  Rio  Cana,  Dominican  Republic,  but  has  more 
acute  umbos  and  coarser  sculpture.  A  similar  species  was  collected 
from  the  Gurabo  formation  on  Rio  Gurabo,  Dominican  Republic. 
C.  xena  also  closely  resembles  C.  duplinianus  (Dali),  from  the  Duplin 
and  Waccamaw  marls  of  North  Carolina,  but  is  less  inflated,  more 
elongate  and  has  more  acute  umbos. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No. 
352798). 

Superfamily  CARDITACEA. 

Family  CARDITIDAE. 

Genus  CARDITA  Lamarck. 

Section  CARDITA  s.  s. 

Lamarck,  1799,  Memoires  de  la  Societe  d’Histoire  Naturelle  de  Paris,  p.  86. 

Type  (by  monotypy). — Chama  calyculata  Linne.  Recent,  Medi¬ 
terranean  Sea. 

The  following  is  a  description  of  the  section  Cardita  s.  s. : 

Shell  medium-sized,  mytiloid,  very  inequilateral,  ventral  margin  insinu¬ 
ated  and  slightly  gaping  at  anterior  end;  lunule  very  small,  deeply  de- 


PELECYPODS. 


99 


pressed,  limited  by  deep  groove;  sculpture  consisting  of  beaded  radial  ribs; 
hinge  of  right  valve  consisting  of  2  cardinals,  the  posterior  one  (36) 
elongate  and  club-shaped,  the  anterior  one  (3a)  partly  fused  to  border  of 
lunule,  and  an  obscure  anterior  lateral;  hinge  of  left  valve  consisting  of  2 
cardinals,  the  posterior  one  (46)  elongate,  the  anterior  one  (2)  obscurely 
bifid,  and  a  small  pointed  anterior  lateral;  inner  margin  of  valve  coarsely 
fluted  except  at  byssal  gape. 

Cardita  s.  s.  is  not  represented  in  the  Bowden  formation.  There  are 
no  living  West  Indian  or  east  American  species.  C.  caribbeanensis 
Olsson,  recently  described  from  the  Gatun  formation  of  Costa  Rica, 
is  the  only  American  fossil  species. 

Section  GLANS  Megerle  von  Miihlfeld. 

Megerle  von  Miihlfeld,  1811,  Gesellschaft  naturforschender  Freunde  zu 
Berlin,  Magazin  fiir  die  neuesten  Entdeckungen  in  der  gesammten 
Naturkunde,  year  5,  p.  68. 

Type  (by  monotypy). — Chama  trapezia  Gmelin.  Recent,  Medi¬ 
terranean  Sea. 

The  following  is  a  description  of  the  section  Gians: 

Shell  medium-sized,  subquadrate,  inequilateral,  strongly  inflated,  poste¬ 
rior  margin  truncated;  lunule  small,  deeply  depressed;  sculpture  consisting 
of  strongly  beaded  radial  ribs;  hinge  of  right  valve  consisting  of  2  cardinals, 
the  posterior  one  (36)  elongate  trigonal,  the  anterior,  one  (3a)  almost 
completely  fused  to  the  hinge  margin,  and  double  anterior  and  single 
posterior  laterals;  hinge  of  left  valve  consisting  of  2  cardinals,  the  poste¬ 
rior  one  (46)  elongate,  and  single  anterior  and  double  posterior  laterals; 
inner  margin  of  valve  coarsely  fluted. 

The  outline  of  the  shell  and  the  prominent  laterals  separate  this 
section  from  Cardita  s.  s.  The  hinge  of  the  Bowden  species,  C.  scabri - 
costata  differs  from  the  hinge  of  the  type,  as  its  right  anterior  cardinal 
(3a)  is  more  distinct;  the  right  posterior  cardinal  (36)  is  less  trigonal; 
and  the  left  anterior  cardinal  (2)  is  more  trigonal.  C.  scabricostata 
has  commonly  been  placed  in  the  genus  V enericardia,  probably  be¬ 
cause  of  its  outline,  although  it  has  much  more  prominent  laterals 
than  V .  imbricata  (Gmelin),  the  type  of  V enericardia.  The  hinge  of 
C.  scabricostata  closely  resembles  the  hinge  of  species  like  C.  inter¬ 
media  (Brocchi),  from  the  Pliocene  of  Italy. 

Living  species  of  Cardita  (Gians),  which  like  the  fossil  species  fre¬ 
quently  are  called  V enericardia,  are  widely  distributed. 

Cardita  (Gians)  scabricostata  Guppy. 

(Plate  12,  Figures  7  to  9.) 

Cardita  scabricostata  Guppy,  1866,  Quart.  Jour.  Geol.  Soc.  London,  vol  22, 
p.  293,  plate  18,  fig.  10.  Guppy  (part),  1874,  Geol.  Mag.,  dec.  2,  vol.  1, 
p.  442,  (list).  Not  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol.  15, 
p.  252  (=  C.  islahispaniolae  Maury).  Not  Guppy,  1876,  Quart.  Jour. 
Geol.  Soc.  London,  vol.  32,  p.  531  (=  C.  islahispaniolae  Maury). 


100 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Venericardia  scabricostata  (Guppy),  Dali  (part),  1903,  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  6,  p.  1428.  ?  Hubbard,  1921, 

Scientific  Survey  of  Porto  Rico  and  the  Virgin  Islands,  vol.  3,  part  2, 
p.  108,  New  York  Acad.  Sci.  Not  Maury,  1917,  Bull.  Amer.  Paleon¬ 
tology,  vol.  5,  p.  362,  plate  59,  fig.  1.  Not  Olsson,  1922,  Bull.  Amer. 
Paleontology,  vol.  9,  pp.  388-389,  plate  32,  figs.  14,  17. 

The  following  is  the  original  description  of  this  species: 

Shell  suborbicular,  nearly  as  high  as  wide,  with  about  18  regularly 
nodosely  nuricate  impressed  ribs;  posterior  margin  nearly  straight,  form¬ 
ing  an  angle  with  the  ventral  margin,  which  is  rounded;  anterior  margin 
rounded;  umbos  prominent;  margins  strongly  crenate,  hinge  with  2  teeth,  of 
which  the  posterior  one  is  long  and  narrow. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  moderately  inflated,  very  inequilateral,  subquadrate;  anterior 
margin  rounding  broadly  into  base,  base  slightly  curved  and  subparallel 
to  the  gently  curved  posterior  dorsal  margin;  posterior  margin  obliquely 
subtruncate,  joining  dorsal  margin  by  a  broad  curve;  umbos  almost  at 
anterior  end  of  shell,  moderately  wide  and  high;  lunule  small,  deeply  de¬ 
pressed;  sculpture  consisting  of  19  to  22  radial  ribs  bearing  strong  rounded 
transverse  beads;  first  few  anterior  ribs  separated  by  wider  interspaces; 
succeeding  ribs  up  to  the  posterior  slope  terraced  on  both  sides,  the  beaded 
part  forming  a  rounded  keel,  interspaces  slightly  narrower;  beyond  the 
posterior  slope  the  lower  terraced  part  of  the  ribs  disappears,  the  ribs  are 
reduced  in  width,  and  the  interspaces  become  correspondingly  wider,  the 
last  3  posterior  ribs  suddenly  widen  and  bear  beads  that  are  more  com¬ 
pressed  at  their  ends  or  even  spinose  and  are  directed  toward  the  posterior 
margin;  on  the  terraced  ribs  the  beads  continue  across  the  terraces  as  ob¬ 
scure  undulations;  very  fine  concentric  striae  and  coarser,  irregular  con¬ 
centric  threads  lie  on  the  terraces  and  in  the  interspaces;  hinge  of  right 
valve  consisting  of  2  cardinals,  the  anterior  one  (3a)  small  and  partly  fused 
to  the  hinge-margin,  the  posterior  one  (36)  elongate,  and  anterior  and 
posterior  laterals,  the  anterior  one  double;  hinge  of  left  valve  consisting  of 
2  cardinals,  the  anterior  one  (2)  trigonal,  the  posterior  one  (46)  narrow 
and  elongate,  and  anterior  and  posterior  laterals,  the  posterior  one  double. 

Length  19  mm.;  height  19.2  mm.;  diameter  (left  valve)  6.2  mm. 

On  some  shells  a  small  secondary  radial  lies  in  one  of  the  two  inter¬ 
spaces  near  the  posterior  margin.  Young  valves  are  more  orbicular 
than  adults;  the  terrace  on  their  median  ribs  is  indistinct;  and  the 
beads  on  the  ventral  part  of  the  posterior  ribs  are  more  scaly. 

C.  scabricostata  is  very  similar  to  a  common  species  in  the  Gurabo 
formation  of  the  Dominican  Republic,  which  has  been  described  as 
Venericardia  islahispaniolae  by  Maury.  The  Bowden  species  is 
smaller  and  has  more  strongly  terraced  ribs,  smaller  left  anterior 
cardinal  (2),  and  stronger  laterals,  which  are  more  distant  from  the 
cardinals.  The  species  described  as  “ Venericardia  scabricostata”  by 
Maury  from  the  Cercado  formation  is  entirely  different.  It  is  more 
orbicular  than  the  Bowden  species  and  has  unterraced  ribs  and  weak 


PELECYPODS. 


101 


laterals.  The  Miocene  species  from  Costa  Rica  described  by  Olsson 
as  “V enericardia  scabricostata”  is  not  at  all  similar  to  the  Bowden 
species. 

The  small  “V enericardia”  from  the  Lares  limestone  (middle  or 
upper  Oligocene)  of  Porto  Rico  described  by  Hubbard  probably  is  a 
different  species. 

Type  material. — Holotype  (British  Museum,  Natural  History,  Geo¬ 
logical  Department  No.  64087). 

Genus  VENERXCARDIA  Lamarck. 

Subgenus  VENERICARDIA  s.  s. 

Lamarck,  1801,  Systeme  des  Animaux  sans  Vertebres,  p.  123. 

Type  ( by  subsequent  designation ,  Gray  1847). — Venus  imbricata 
Gmelin.  Eocene,  Paris  Basin. 

The  following  is  a  description  of  the  subgenus  V enericardia  s.  s.: 

Shell  thick,  medium-sized,  cardiform,  orbicular-rhomboidal,  strongly  in¬ 
flated;  umbos  prosogyrate;  lunule  very  small,  deeply  depressed,  bounded  by 
a  deep  groove;  sculpture  consisting  of  beaded  radial  ribs;  hinge-platform 
wide;  hinge  of  right  valve  consisting  of  2  cardinals,  the  anterior  one  (3a) 
very  small,  the  posterior  one  (36)  elongate,  and  an  obscure  posterior 
lateral;  hinge  of  left  valve  consisting  of  2  cardinals,  the  posterior  one  (46) 
elongate,  and  an  obscure  anterior  and  posterior  lateral;  inner  margin  of 
valve  coarsely  fluted. 

There  are  no  Bowden  species  of  V enericardia  s.  s. 

Subgenus  PLEUROMERIS  Conrad. 

Conrad,  1867,  American  Journal  of  Conchology,  vol.  3,  p.  12. 

Type  ( by  monotypy). — Pleuromeris  decemcostata  Conrad  (=Car- 
dita  tridentata  Say).  Miocene  and  Pliocene,  middle  Atlantic  states. 

The  following  is  a  description  of  the  subgenus  Pleuromeris: 

Shell  small,  cardiform,  slightly  inequilateral,  strongly  inflated;  lunule 
and  escutcheon  small,  lunule  limited  at  hinge-margin  by  a  ridge;  sculpture 
consisting  of  strongly  beaded  radial  ribs;  hinge  of  right  valve  consisting 
of  a  central  large  trigonal  cardinal  (36)  and  double  anterior  and  single 
posterior  laterals;  hinge  of  left  valve  consisting  of  an  anterior  (2)  and 
posterior  (46)  cardinal,  the  posterior  one  elongate,  and  single  anterior  and 
double  posterior  laterals;  inner  margin  of  valve  coarsely  fluted. 

The  Bowden  species  V.  acaris  Dali  has  been  placed  in  the  subgenus 
Pteromeris  Conrad,  the  type  of  which,  V.  radians  Conrad  (—V.  per - 
plana  Conrad),  is  flattened  and  has  bifid  cardinals.  V.  acaris  is  more 
inequilateral  than  the  type  of  Pleuromeris  and  has  a  thickened  ridge 
at  the  inner  margin  of  the  escutcheon.  The  hinges  of  the  two  species 
are  similar,  although  the  left  anterior  cardinal  (2)  of  the  Bowden 
species  is  more  elongate. 

Pleuromeris  is  an  American  group  of  small  Venericardias  first 
appearing  in  the  Eocene. 


102 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Venericardia  (Pleuromeris)  acaris  Dali. 

(Plate  12,  Figures  10  to  12.) 

Venericardia  ( Pteromeris )  acaris  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  6,  p.  1434,  plate  56,  fig.  4. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  plump,  inequilateral,  the  full  but  rather  low  beaks  situated 
near  the  posterior  third;  anterior  end  longer,  obliquely  produced,  rounded, 
posterior  dorsal  border  descending  much  more  steeply,  subangular  at  the 
lower  posterior  termination;  sculpture  of  about  18  broad,  flattened  radial 
ribs  separated  by  narrow  sulci  and  crossed  by  small,  arcuate,  raised  threads, 
convex  dorsally,  the  ends  of  these  threads  projecting  sometimes  gives  a 
punctate  effect  to  the  sulci;  there  is  a  small,  narrow  lunule  and  escutcheon 
apparently  quite  smooth;  hinge  normal,  the  lateral  distinct;  the  inner 
margins  sharply  crenulate,  the  ligament  and  resilium  wholly  external. 
Length  2.5,  height  2.5,  diameter  2.0  mm. 

Type  locality. — Bowden,  Jamaica. 

The  sculpture  consists  of  18  to  20  ribs,  ornamented  with  low  rounded 
beads.  A  short  row  of  oblique  rugae  representing  the  beads  of  the 
adjoining  ribs  extends  along  the  margin  of  the  lunule.  At  the  margin 
of  the  escutcheon  lies  a  similar  but  shorter  row.  The  lunule  is- sharply 
set  off  from  the  sculptured  part,  but  the  escutcheon,  which  is  longer 
and  narrower  than  the  lunule,  usually  is  less  distinct.  Both  lunule 
and  escutcheon  have  a  thickened  ridge  at  the  hinge,  especially  on  the 
right  valve.  The  height  of  the  shell  usually  exceeds  the  width. 

This  species  is  less  orbicular  and  has  narrower  interspaces  than 
V.  (P.)  conradiana  Gabb,1  from  Costa  Rica. 

Type  material. — 5  cotypes  (U.  S.  Nat.  Mus.  No.  135677). 

Superfamily  CHAMACEA. 

Family  CHAMIDAE. 

Genus  CHAMA  Linne. 

Linne,  1758,  Systeme  Naturae,  ed.  10,  p.  691. 

Type  (by  subsequent  designation,  Gray  1847). — Chama  lazarus 
Linne.  Recent,  Indian  Ocean. 

The  following  is  a  description  of  the  genus  Chama: 

Shell  medium-sized,  orbicular,  inequivalve,  attached  by  left  valve;  apex 
dextrally  twisted  when  shell  is  viewed  in  attached  position;  sculpture  con¬ 
sisting  of  foliaceous  concentric  lamellae;  prodissoconch  very  small,  gener¬ 
ally  sculptured  with  closely  spaced  radial  threads  and  more  distant  con¬ 
centric  lamellae;  hinge  of  right  valve  consisting  of  a  long  curved  tooth 
paralleling  the  hinge-margin,  its  lower  side  roughened,  obscurely  divided 
into  two  parts,  a  small  narrow  tooth  lying  above  the  larger  one,  and  a 

1  W.  M.  Gabb.  Jour.  Acad.  Nat.  Sci.  Philadelphia,  ser.  2,  vol.  8,  p.  377,  plate  47,  fig.  79.  1881. 

Gabb’s  specimen  came  from  beds  considered  of  Pliocene  age,  but  at  that  time  it  was  not  known 
that  Miocene  beds  crop  out  at  Limon.  V.  (P.)  conradiana  limonensis  Olsson  (Bull.  Amer. 
Paleontology,  vol.  9,  p.  389,  plate  29,  figs.  19,  20,  1922),  from  beds  of  known  Miocene  age  at 
Limon,  may  be  the  same  form. 


PELECYPODS. 


103 


rudimentary  posterior  lateral;  hinge  of  left  valve  consisting  of  a  heavy 
tooth  at  the  base  of  the  hinge  plate,  grooved  on  its  upper  side,  a  longer 
tooth-like  mass  paralleling  the  ligament,  obscurely  divided  into  two  parts, 
and  a  rudimentary  posterior  lateral;1  posterior  adductor  scar  more  elon¬ 
gate  than  anterior. 

The  living  species  of  Chama,  like  the  Teritary  species,  are  widely 
distributed  in  the  warm  shallow  seas.  They  are  most  abundant  among 
coral  reefs. 

Key  to  the  Bowden  species  oj  Chama. 


Shell  small,  sculpture  of  right  valve  not  spinose .  C.  involuta 

Shell  large,  sculpture  of  right  valve  spinose .  C.  macerophylla 


Chama  involuta  Guppy. 

(Plate  12,  Figures  13  to  17.) 

Chama  macrophylla  Gabb  (part,  not  Chemnitz),  1873,  Trans.  Amer.  Philos. 
Soc.  n.  s.,  vol.  15,  p.  251. 

Chama  involuta  Guppy,  1873,  Proc.  Sci.  Assoc.  Trinidad,  vol.  2,  part  2,  p.  86, 
plate  2,  fig.  5.  Guppy,  1874,  Geol.  Mag.  decade  2,  vol.  1,  p.  436,  plate 
17,  figs.  5 a-5c;  p.  442  (list).  Guppy,  1876,  Quart.  Jour.  Geol.  Soc. 
London,  vol.  32,  p.  531.  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  6,  p.  1398.  Maury,  1917,  Bull.  Amer.  Paleontology, 
vol.  5,  p.  363,  plate  59,  figs.  4  to  6.  ?  Hubbard,  1921,  Scientific  Survey 

of  Porto  Rico  and  the  Virgin  Islands,  vol.  3,  part  2,  p.  109,  New  York 
Acad.  Sci.  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  73, 
p.  416. 

The  following  is  the  original  description  of  this  species: 

Left  (attached)  valve  deep  internally,  very  convex  externally,  often 
spiral,  completing  a  turn  and  a  half,  covered  externally  with  distant  large 
foliaceous  scales  more  or  less  erect,  between  which  are  small  irregular  di¬ 
verging  granose  ridges.  Right  valve  patulous,  ornamented  with  numerous 
close  concentric  sinuous  foliaceous  laminae.  Umbos  large,  prominent,  spiral. 
Margin  and  laminar  cardinal  tooth  crenate. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  thin  or  moderately  heavy,  usually  suborbicular  or  elongate- 
subovate;  left  valve  attached,  irregular,  very  convex,  umbos  prominent, 
strongly  twisted;  sculpture  consisting  of  relatively  coarse,  slightly  im¬ 
bricating  concentric  lamellae,  at  intervals  extended  and  elevated  into 
short  scales  arranged  in  more  or  less  obscure  radial  series;  irregular  in¬ 
terrupted  swollen  radial  threads  extend  over  the  lamellae;  right  valve  com¬ 
pressed  or  moderately  inflated  in  umbonal  region;  sculptured  with  closely 
spaced  projecting  frilled  lamellae;  inner  margin  of  right  valve  finely  cor¬ 
rugated;  on  the  left  valve  corrugations  usually  are  absent  on  the  margin, 
except  on  the  upper  posterior  margin,  and  on  some  valves  faint  radial 
threads  are  visible  on  the  inner  surface. 

A  left  valve:  length  12  mm.;  height  14  mm.;  diameter  5.8  mm.  A  right 
valve:  length  11.7  mm.;  height  12.5  mm.;  diameter  4.8  mm. 


1  Dentition  after  Odhner,  1918  (see  reference  on  p.  105). 


104 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Some  of  the  numerous  valves  of  this  species  are  larger  than  the 
ones  measured.  The  largest  left  valve  has  the  following  dimensions: 
length  18  mm.;  height  20.5  mm.;  diameter  10  mm. 

The  sculpture  of  the  attached  (left)  valve  is  very  irregular.  The 
radial  scales,  which  rarely  are  extended  forming  spines,  may  disap¬ 
pear,  but  the  peculiar  pustular  radial  sculpture  usually  persists.  On 
right  valves  the  number  of  concentric  lamellae  and  the  relative  coarse¬ 
ness  of  the  flutings  vary.  The  prodissoconch  is  preserved  on  a  few 
shells.  It  is  small,  subquadrate ;  umbo  at  anterior  end ;  sculpture  con¬ 
sisting  of  6  to  7  distant,  regularly  spaced,  sharply  raised,  and  slightly 
recurved  concentric  lamellae  and  intervening  obscure,  fine  concentric 
striae ;  radial  sculpture  obscure. 

The  small  size,  vermicular,  scabrous,  or  spiny  sculpture  of  the 
attached  left  valve,  and  the  numerous  finely  fluted  lamellae  of  the 
right  valve  are  characteristic  features  of  this  species.  Shells  from 
both  the  Cercado  and  Gurabo  formations  of  the  Dominican  Republic 
seem  to  be  this  species.  The  Cercado  shells  are  smaller  than  shells 
from  Bowden.  The  concentric  lamellae  on  the  left  valves  of  Gurabo 
shells  are  more  distant  than  on  Bowden  shells  and  the  sculpture  of 
right  valves  is  less  foliaceous,  but  the  prodissoconchs  are  similar.  The 
left  valve  of  C.  chipolana  Dali,  described  from  the  Chipola  formation 
of  Florida,  has  more  numerous  radials  and  larger  spines;  the  right 
valve  has  less  foliaceous  concentric  sculpture.  It  is  not  likely  that 
the  large  Chama  described  by  Hubbard  from  the  Quebradillas  lime¬ 
stone  (lower  Miocene)  of  Porto  Rico  is  the  Bowden  species. 

Other  localities. — Cercado  (lower  Miocene),  and  Gurabo  (middle 
Miocene)  formations,  Dominican  Republic. 

Type  material. — 11  cotypes  (U.  S.  Nat.  Mus.  No.  115537). 

Chama  macerophylla  Gmelin. 

(Plate  12,  Figures  18,  19.) 

Macerophylla,  Flos  Macis,  etc.,  Chemnitz,  1784,  Conch.  Cab.,  vol.  7,  pp. 
101,  149,  plate  52,  figs.  514,  515. 

Chama  macerophylla  Gmelin,  1792,  Syst.  Nat.,  ed.  12,  vol.  6,  p.  3305.  Dali,  1903, 
Trans.  Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  6,  pp.  1403-1404. 

Chama  citrea  Gmelin,  1792,  Syst.  Nat.,  ed.  12,  p.  3305. 

Chama  macrophylla  Gmelin,  Hanley,  1843,  Descr.  Cat.  Rec.  Biv.  Shells, 
p.  226.  Reeve,  1846-1847,  Conch.  Icon.,  vol.  4,  Chama,  plate  2,  fig.  6; 
plate  8,  fig.  6b.  d’Orbigny,  1853,  in  de  la  Sagra,  Hist,  phys.,  polit.  et 
natur.  de  l’lle  de  Cuba,  Mollusques,  vol.  2,  p.  363.  (French  ed.).  Gabb 
(part),  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol.  15,  p.  251.  Gabb,  1881, 
Jour.  Acad.  Nat.  Sci.  Philadelphia,  ser.  2,  vol.  8,  p.  375. 

The  following  is  the  original  description  of  this  species: 

Ch.  testa  rotundata  seriatim  lamellata,  margine  interno  crenulata. 

The  following  is  a  description  of  a  Bowden  specimen  of  this  species : 

Shell  medium-sized,  irregularly  subova te;  attached  by  left  valve;  right 
valve  moderately  convex  at  posterior  end,  compressed  toward  anterior 


PELECYPODS. 


105 


margin;  umbo  large  for  size  of  shell,  twisted  about  one  and  a  half  turns; 
sculpture  consisting  of  irregular,  more  or  less  overlapping  concentric 
lamellae,  frilled  and  extended  at  irregular  intervals  into  spines  bearing  fine 
obscure  radial  striae. 

Right  valve:  length  27  mm.;  height  23  mm.;  diameter  8  mm. 

A  right  valve  seems  to  be  this  species.  The  much  larger  size,  larger 
umbo,  more  foliaceous  and  spinose  lamellae  bearing  fine  radial  striae, 
separate  this  valve  from  right  valves  of  C.  involuta. 

Other  localities . — Miocene,  Dominican  Republic.  Pliocene,  Limon, 
Costa  Rica.  Pleistocene,  the  Antilles  and  Curagao.  Living,  Tampa 
to  Curasao  and  Santa  Marta  in  shallow  water  to  287  fathoms. 

Genus  ECHINOCHAMA  Fischer. 

Fischer,  1887,  Manuel  de  Conchyliologie,  p.  1049. 

Type  {by  monotypy). — Chama  arcinella  Linne.  Recent,  West 
Indies. 

The  following  is  a  description  of  the  genus  Echinochama: 

Shell  medium-sized,  suborbicular,  subequivalve,  adult  not  attached, 
young  shell  attached  by  right  valve;  umbos  strongly  prosogyrate;  lunule 
large,  deeply  depressed;  sculpture  consisting  of  pits  and  spinose  radial 
ribs;  prodiscoconch  large,  elongate;  hinge  of  right  valve  consisting  of  a 
heavy  furrowed  anterior  callosity,  a  posterior  row  of  denticles  paralleling 
the  ligament,  and  a  rudimentary  posterior  lateral;  hinge  of  left  valve  con¬ 
sisting  of  an  anterior  row  of  small  denticles,  a  furrowed  socket,  a  heavy 
posterior  tooth,  its  upper  surface  denticulate  and  its  inner  surface  furrowed, 
and  a  rudimentary  posterior  lateral;1  margin  of  valve  coarsely  fluted; 
inner  margin  finely  corrugated. 

Echinochama  is  a  strictly  American  tropical  group  of  Chamas.  One 
species  (the  genotype  E.  arcinella )  lives  in  the  West  Indies,  and  an¬ 
other  species  (E.  calijornica  Dali)  lives  on  the  Pacific  coast  off  Lower 
California.  The  genus  first  appears  in  lower  Miocene  deposits  in  the 
West  Indies  (Cercado  formation,  Dominican  Republic).  It  is  con¬ 
spicuous  in  the  middle  Miocene  deposits  of  the  West  Indies  and 
Central  America.  The  living  E.  arcinella  occurs  in  the  Shoal  River 
formation  (middle  Miocene)  and  Choctawhatchee  marl  of  Florida. 
As  Echinochama  is  a  characteristically  tropical  genus,  these  deposits 
may  have  been  laid  down  in  warm  temperate  waters. 

As  a  result  of  an  extensive  study  of  the  Chamidae,  Odhner2  has 
restricted  the  name  Chama  to  the  so-called  “normal”  Chamas  at¬ 
tached  by  the  left  valve,  and  proposed  the  new  genus  Pseudochama 
for  the  “inverse”  Chamas  attached  by  the  right  valve.  According  to 
Odhner,  Echinochama  is  a  modified  Pseudochama ,  and  he  considered 


1  Dentition  after  Odhner,  1918  (see  reference  below). 

2  N.  H.  J.  Odhner.  Results  of  Dr.  E.  Mjobergs  Swedish  scientific  expenditiona  to  Australia 
1910-1913,  xvn,  Mollusca:  Kungl.  Svenska  Vetenskapsakademiens  Handlingar,  vol,  52,  No.  16: 
pp.  28-31.  1917.  Studies  in  the  morphology,  the  taxonomy,  and  the  relations  of  Recent  Chamidae, 
Kungl.  Svenska  Vetenshapsakademiens  Handlingar,  vol.  59,  No.  3,  102  pp.,  8  plates.  1918. 


106 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


it  a  subgenus  of  Pseudochama.  This  arrangement  violates  the  rules 
of  nomeclature,  as  Echinochama,  the  earlier  name,  would  have  to  be 
the  generic  name  and  Pseudochama  the  subgeneric.  Echinochama  is 
the  only  representative  of  the  “inverse”  Chamas  in  the  Bowden 
formation. 

Echinochama  antiquata  Dali. 

(Plate  13,  Figures  1  to  4.) 

Chama  arcinella  Guppy  (not  Linne),  1866,  Quart.  Jour.  Geol.  Soc.  London, 
vol.  22,  p.  294.  Guppy  (part,  not  Linne),  1874,  Geol.  Mag.  decade  2, 
vol.  1,  p.  442  (list). 

Echinochama  antiquata  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  6,  pp.  1404-1405,  plate  54,  fig.  9.  ?  Maury,  1920, 

Scientific  Survey  of  Porto  Rico  and  the  Virgin  Islands,  vol.  3,  part  1, 
p.  30,  New  York  Acad.  Sci.  Not  Maury,  1917,  Bull.  Amer.  Paleontology, 
vol.  5,  p.  365,  plate  59,  fig.  10  (  =  E.  trachyderma  Pilsbry  and  Johnson). 
Not  Olsson,  1922,  Bull.  Amer.  Paleontology,  vol.  9,  pp.  390-391,  plate 
31,  fig.  8. 

The  following  is  the  original  description  of  this  species: 

Shell  large,  subquadrate,  with  an  almost  obsoletely  rectilinear  base, 
slightly  arched  posterior  and  dorsal  edges,  and  excavated  anterior  end; 
valves  less  convex  than  in  E.  arcinella  and  with  less  prominent  and  inflated 
beaks,  larger  and  impressed  lunule;  the  number  of  ribs  varies  from  22  to 
31,  low  with  subequal  interspaces,  the  spines  very  short  and  scale-like, 
except  on  a  single  median  rib,  where  they  are  triangular  and  somewhat 
longer  than  on  the  rest;  surface  sculpture  more  pustular  and  less  regular 
than  in  E.  arcinella.  Length  50,  height  48,  diameter  about  40  mm.  ex¬ 
clusive  of  the  spines. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  large,  massive,  equivalve,  inequilateral;  umbos  anterior,  moderately 
inflated  and  moderately  high;  lunule  large,  deeply  depressed,  its  median 
part  raised  toward  margin;  sculpture  consisting  of  20  to  30  low,  rounded 
radial  ribs,  separated  by  interspaces  of  about  the  same  width;  on  the 
posterior  half  of  shell  the  ribs  are  small,  but  increase  in  width  toward 
center  where  there  is  a  prominent  rib;  on  the  anterior  half  the  ribs  are 
fewer,  but  wider  and  higher,  and  decrease  in  size  anteriorly,  but  near  the 
margin  of  the  lunule  again  becoming  larger;  on  the  dorsal  margin  of  the 
right  valve  are  1  or  2  more  or  less  irregular  ribs,  much  more  prominent 
than  adjoining  ones;  ribs  ornamented  with  short  lamellar  spines,  most 
prominent  on  the  large  median  rib  and  on  the  posterior  ribs,  often  taking 
the  form  of  small  irregular  beads;  interspaces  and  lunule  irregularly  pitted; 
concentric  sculpture  consisting  of  irregular  slightly  imbricating  lamellae 
near  margins  and  continuing  across  lunule;  ventral  margin  of  the  shell 
slightly  undulated  by  the  anterior  ribs;  inner  margin  finely  corrugated. 

Length  52.5  mm.;  height  52  mm;,  diameter  (right  valve)  21  mm. 

The  large  massive  shells  of  this  species  are  very  conspicuous.  The 
prominent  irregularly  spinose  rib,  or  ribs,  adjacent  to  the  dorsal 
margin,  is  a  constant  feature  on  right  valves,  but  is  absent  on  left 


PELECYPODS. 


107 


valves.  Some  shells  have  a  shallow  groove  near  the  dorsal  margin. 
The  part  of  the  shell  between  this  groove  and  the  prominent  median 
rib  is  slightly  raised.  Traces  of  reddish-brown  coloration  are  visible 
on  the  interior  surface  of  one  valve. 

The  differences  between  E.  antiquata  and  E.  arcinalla  (Linne),  the 
living  West  Indian  species,  are  discussed  by  Dali.  In  addition, 
E.  antiquata  has  more  numerous,  narrower  ribs  and  much  shorter 
spines.  Young  shells  of  the  Bowden  species  have  fewer  ribs  and  rela¬ 
tively  longer  spines  than  adults  and  therefore  more  closely  resemble 
the  living  species.  The  Bowden  species  is  similar  to  the  living  West 
Coast  species,  E.  calif ornica  Dali,  but  has  more  numerous  and  shorter 
spines.  E.  tr  achy  derma  Pilsbry  and  Johnson,  which  has  been  con¬ 
fused  with  E.  antiquata,  is  confined  to  the  Gurabo  formation  in  the 
Dominican  Republic.  It  has  fewer  and  less  spinose  ribs  than  the 
Bowden  species,  and  the  exterior  is  more  pitted.  In  the  smaller 
species,  E .  yaquensis  Maury,  which  also  is  confined  to  the  Gurabo 
formation,  these  differences  are  more  pronounced.  The  Miocene 
species  from  Costa  Rica,  described  by  Olsson  as  E.  antiquata,  is 
smaller  than  specimens  from  Bowden  and  has  fewer  ribs.  An  internal 
cast  from  Porto  Rico  was  referred  by  Maury  to  E .  antiquata. 

Type  material. — 6  cotypes  (U.  S.  Nat.  Mus.  No.  135740). 

Superfamily  LUCINACEA. 

Family  LUCINIDAE. 

Genus  CODAKIA  Scopoli. 

Section  CODAKIA  s.  s. 

Scopoli,  1777,  Introductio  ad  Historiam  naturalem,  sistens  genera  Lapidum, 
Plantarum  et  Animalium  hactenus  detecta,  caracteribus  essentialibus 
donata,  in  tribus  divisa,  subinde  ad  leges  Naturae,  p.  398. 

Type  {by  monotypy). — Chama  codok  Adanson  (?= Venus  punc¬ 
tata  Linne).  Recent,  west  coast  of  Africa.1 

The  following  is  a  description  of  the  section  Codakia  s.  s. : 

Shell  large,  suborbicular,  moderately  inflated;  lunule  small,  deeply  de¬ 
pressed;  sculpture  consisting  of  radial  grooves  and  striae,  crossed  by  in¬ 
cremental;  ligament  and  resilium  large,  deeply  inset;  hinge  of  right  valve 
consisting  of  a  prominent  anterior  lateral  close  to  the  cardinals,  anterior 
(3a)  and  middle  (36)  cardinals,  and  a  small  posterior  lateral;  hinge  of 
left  valve  consisting  of  large  double  anterior  laterals,  anterior  (2)  and 
middle  (46)  cardinals,  and  small  double  posterior  laterals;  inner  margin  of 
valve  slightly  wrinkled. 

Codakia  s.  s.  is  a  tropical  genus  living  in  West  Indian  and  west 
African  waters.  During  Tertiary  time  it  was  more  widely  distributed, 
as  several  species  are  recorded  from  the  Mediterranean  region  and 
other  parts  of  Europe.  The  earliest  European  species  is  of  Eocene 


JThe  description  is  based  on  Venus  punctata  Linn6. 


108 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


age,  but  Miocene  deposits  have  furnished  the  earliest  American 
species. 

Key  to  the  Bowden  species  of  Codakia  s.  s. 

Shell  weakly  sculptured .  C.  (C.)  spinulosa 

Shell  strongly  sculptured .  C.  ( C .)  lomonea 

Codakia  (Codakia)  spinulosa  Dali. 

(Plate  13,  Figures  5,  6.) 

Codakia  spinulosa  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia, 
vol.  3,  part  6,  pp.  1346-1347,  plate  52,  fig.  19. 

The  following  is  the  original  description  of  this  species: 

Shell  nearly  orbicular,  moderately  and  regularly  convex,  solid,  with 
pointed,  low,  prosogyrate  beaks;  lunule  small,  deep,  cardiform;  sculpture  of 
small,  low,  flattish,  indistinct  radials  with  slightly  excavated,  narrower 
interspaces;  these  are  crossed  by  indistinct,  concentric  threads,  incremental 
lines,  and  occasional  ridges  due  to  resting  stages;  at  what  would  be  the 
intersections  if  the  concentric  sculpture  were  better  developed,  the  shell 
shows  small,  squarish  nodulations  which  towards  the  ends  and  dorsal 
margins  become  minutely  spinulose;  the  right  valve  has  the  hinge  well 
developed,  the  anterior  lateral  large  and  strong,  the  posterior  obsolete; 
the  posterior  cardinal  slightly  grooved;  margin  with  traces  of  crenulation 
anteriorly;  scars  normal.  Height  28.0,  length  29.0,  diameter  12.0  mm. 

Type  locality. — Bowden,  Jamaica. 

This  species  is  known  only  from  one  right  valve.  The  concentric 
sculpture  consists  of  pustular  beads  that  are  eroded  from  part  of  the 
shell.  The  characteristic  features  are  the  pustular  sculpture  and  small 
deep  lunule.  There  is  no  possibility  of  confusing  this  species  with  the 
living  West  Indian  C.  orbicularis  (Linne),  which  ranges  back  to  the 
Pliocene,  because  of  the  much  smaller  size,  more  rounded  outline,  and 
less  pronounced  sculpture  of  the  Bowden  species. 

Type  material. — 5  cotypes,  4  of  which  represent  a  species  of  Pha - 
coides  ( Parvilucina )  (U.  S.  Nat.  Mus.  No.  135713). 

Codakia  (Codakia)  lomonea,  new  species. 

(Plate  13,  Figures  7,  8.) 

The  following  is  a  description  of  this  species: 

Shell  small,  suborbicular,  weakly  inflated,  anterior  end  more  extended 
and  more  convexly  rounded;  lunule  narrow,  moderately  depressed; 
sculpture  consisting  of  32  strong  radials  of  varying  width,  separated  by 
narrower  interspaces;  ribs  bearing  relatively  coarse  beads  arranged  along 
equally  spaced  concentric  lines,  the  beads  becoming  compressed  and 
sharper  toward  margins;  hinge  of  right  valve  consisting  of  2  cardinals,  the 
posterior  (35)  larger  and  obscurely  bifid,  and  an  anterior  and  posterior 
lateral,  the  posterior  somewhat  obscured  by  the  ligament;  inner  margin  of 
the  valve  obscurely  wrinkled;  interior  bearing  obscure  radial  markings. 

Length  14  mm.;  height  13  mm.;  diameter  (right  valve)  2.5  mm. 

The  holotype,  a  right  valve,  is  the  only  specimen  of  this  species. 
It  is  characterized  by  its  strong  sculpture  and  is  similar  to  the  living 


PELECYPODS. 


109 


West  Indian  species,  C.  orbicularis  Linne,  though  smaller  and  more 
strongly  sculptured. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352803). 

Section  JAGONIA  Recluz. 

Recluz,  1869,  Actes  de  la  Societe  Linneenne  de  Bordeaux,  vol.  27  (ser.  3,  vol. 

7,)  p.  37. 

Type  (by  original  designation) . — Le  Jagon  Adanson  (=Venus  orbi- 
culata  Montagu).  Recent,  west  coast  of  Africa. 

The  following  is  a  description  of  the  section  Jagonia: 

Shell  medium-sized,  suborbicular,  strongly  inflated;  lunule  small,  deeply 
depressed;  sculpture  consisting  of  narrow  radial  ribs  and  narrow  concentric 
beads;  ligament  narrow;  hinge  resembling  Codakia  s.  s.,  but  the  laterals  are 
more  systemmetrically  situated  with  regard  to  the  cardinals  and  the 
posterior  laterals  are  stronger;  inner  margin  of  valve  weakly  frilled. 

The  living  species  of  Jagonia  are  more  widely  distributed  than 
Codakia  s.  s.,  and  the  Tertiary  species  have  a  correspondingly  more 
extensive  distribution  in  tropical,  subtropical,  and  temperate  faunas. 
Oligocene  deposits  of  the  Paris  Basin  carry  the  earliest  European 
Jagonia.  The  earliest  American  species  is  of  Miocene  age. 

Key  to  the  Bowden  species  of  Jagonia. 


Shell  strongly  inflated,  sculpture  strong .  C.  ( J .)  vendryesi 

Shell  moderately  inflated,  sculpture  moderately  strong .  C.  ( J .)  guppyi 


Codakia  (Jagonia)  vendryesi  Dali. 

(Plate  14,  Figures  1  to  4.) 

Codakia  ( Jagonia )  vendryesi  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  6,  p.  1348,  plate  52,  fig.  4, 

The  following  is  the  original  description  of  this  species: 

This  species  is  the  Oligocene  analogue  of  the  recent  Lucina  antillarum 
Reeve  (=  L.  costata  Orbigny,  not  Tuomey  and  Holmes),  from  which  it 
differs  in  its  more  inequilateral  shell,  sharper  and  more  distinctly  reticulate 
sculpture,  with  finer  and  more  thread-like  radials,  plumper  and  usually 
smaller  shell.  It  is  abundant  in  the  Bowden  marl,  from  which  it  was 
collected  by  Henry  Vendryes,  esq.,  who  sent  it  to  Mr.  Guppy,  and  sub¬ 
sequently  by  Messrs.  Henderson  and  Simpson. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  inequilateral,  lower  part  of  anterior  margin  obliquely  ex¬ 
tended;  umbos  full,  moderately  prominent;  lunule  small,  deep;  dorsal  area 
poorly  defined  except  for  the  difference  in  sculpture;  sculpture  consisting 
of  numerous  fine,  sharply  defined  radials,  typically  several  fascicles,  includ¬ 
ing  usually  2,  but  sometimes  3  radials,  extend  from  the  umbo  to  the  margin, 
and  finer  lower  radials  lie  between  the  fascicles ;  the  more  prominent  radials 
forming  the  fascicles  on  some  shells  become  less  prominent  and  almost  equal 
to  the  others  toward  the  margin ;  on  some  shells  there  are  no  fascicles,  some 


110 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


radials  are  merely  more  prominent  than  others  or  all  are  almost  equal; 
radials  bearing  continuous  rows  of  narrow  prominent  beads,  continuing 
across  interspaces  and  dorsal  areas  as  concentric  threads;  anterior  dorsal 
area  bearing  a  few  weak  radials;  anterior  part  of  posterior  dorsal  area 
bearing  no  radials,  remainder  bearing  a  few  radials  that  become  weaker 
toward  the  margin,  a  very  narrow  area  adjacent  to  the  margin  being  almost 
or  entirely  smooth,  but  not  depressed;  cardinals  and  laterals  strong;  inner 
margin  of  valve  finely  fluted. 

Length  8.2  mm.;  height  9  mm.;  diameter  (right  valve)  3  mm. 

This  species  is  the  most  abundant  of  the  lucinoids,  among  which  it 
is  conspicuous,  because  of  its  sharply  reticulate  sculpture.  The  sculp¬ 
ture  is  very  variable,  presenting  almost  all  gradations  from  fascicles 
of  prominent  radials,  separated  by  finer  ones,  to  virtually  equal 
radials.  On  young  shells  that  have  fascicles  the  radials  in  the 
fascicles  are  fused  for  a  considerable  distance  from  the  umbo  and  the 
finer  intervening  radials  are  more  often  absent  than  on  adults.  Some 
shells  are  more  inflated  than  others.  The  largest  valve  has  the  fol¬ 
lowing  dimensions:  length  9  mm.;  height  9.1  mm.;  diameter  2.9  mm. 

Young  valves  on  which  the  radials  are  almost  equal  may  possibly 
be  confused  with  certain  shells  of  Phacoides  ( Bellucina )  actinus  Dali, 
which  is  less  equilateral,  and  has  fuller  umbos,  coarser  and  more  regu¬ 
lar  radials,  sharp,  thin  concentric  lamellae,  wider  lunule,  an  escut¬ 
cheon,  weaker  cardinals  and  more  elongate  laterals. 

Lucina  antillarum  Gabb  (not  Reeve)  from  an  unknown  horizon  in 
the  Dominican  Republic,  which  Dali  placed  in  synonomy  with  C. 
vendryesi,  has  been  described  as  Phacoides  perplexus  by  Pilsbry  and 
Johnson.  It  has  a  different  hinge  and  different  sculpture. 

Type  material. — 3  cotypes  (U.  S.  Nat.  Mus.  No.  135720). 

Codakia  (Jagonia)  guppyi,  new  name. 

(Plate  14,  Figures  5  to  7.) 

Lucina  textilis  Guppy,  in  Guppy  and  Dali,  1896,  Proc.  U.  S.  Nat.  Mus., 
vol.  19,  p.  326,  plate  30,  fig.  1. 

Codakia  ( Jagonia )  textilis  Guppy,  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  6,  p.  1348. 

Not  Lucina  textilis  Philippi  (=  Codakia  C Jagonia )  textilis ),  1850. 

The  following  is  the  original  description  of  this  species: 

Orbicular,  occasionally  a  little  irregular  in  outline;  decussate  by  some¬ 
what  irregular  fine  radiating  and  concentric  lines;  margins  dentate.  Di¬ 
ameter,  11  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  thin,  surface  usually  irregular,  length  exceeding  height, 
slightly  inequilateral,  anterior  end  extended;  umbo  full,  moderately  high; 
lunule  small,  narrow,  moderately  depressed;  anterior  dorsal  area  poorly 
defined,  posterior  dorsal  area  depressed,  on  some  valves  causing  a  slight 
sinuation  of  the  margin;  sculpture  consisting  of  numerous  weak  radials  of 
irregular  width,  crossed  by  low,  concentric  threads  of  varying  width  and 


PELECYPODS. 


Ill 


irregularly  spaced  incrementals ;  on  the  dorsal  areas  the  radials  are  absent 
or  obscure;  laterals  of  left  valve  weak;  inner  margin  of  valve  finely  fluted. 

Length  14.2  mm.;  height  12.5  mm.;  diameter  (right  valve)  3.8  mm. 

The  concentric  sculpture  is  irregular,  as  most  of  the  valves  are  worn. 
It  consists  of  irregularly  spaced  concentric  threads  of  varying  width 
and  sharpness,  which  usually  are  absent  on  the  median  dorsal  region, 
and  of  incrementals.  Fine  radials  of  varying  width  and  prominence 
usually  cover  the  entire  shell,  except  in  the  umbonal  region.  Both 
sets  of  sculpture  usually  are  conspicuous,  enough  to  produce  a  reticu¬ 
late  effect.  The  left  laterals  are  much  weaker  than  in  the  type  of 
Jagonia. 

The  small  size,  slightly  elongate  outline,  and  fine  radial  sculpture 
are  characteristic  features. 

Type  material. — 5  cotypes,  the  cotypes  of  Lucina  textilis  Guppy 
(U.  S.  Nat.  Mus.  No.  107103). 

Genus  LUCINA  Lamarck. 

Subgenus  LUCINA  s.  s. 

Lamarck,  1799,  Memoires  de  la  Societe  d’Histoire  Naturelle  de  Paris,  p.  84. 

Type  (by  monotypy). — Venus  edentula  Linne.  Recent,  Indo- 
Pacific. 

The  following  is  a  description  of  the  section  Lucina  s.  s.: 

r 

Shell  large,  subspherical,  thin;  lunule  small,  depressed,  escutcheon  absent; 
sculpture  consisting  of  exaggerated  incrementals;  ligament  and  resilium 
external,  deeply  inset;  hinge  edentulous;  inner  margin  of  valve  smooth; 
anterior  adductor  scar  long  and  narrow,  paralleling  the  pallial  line. 

Tertiary  and  living  species  of  Lucina  s.  s.  are  confined  to  American 
and  Pacific  waters.  They  are  conspicuous  in  the  Tertiary  deposits  of 
the  Gulf  States  and  the  West  Indies.  European  representatives  be¬ 
long  to  the  subgenus  Loripinus,  which  has  no  ligament,  and  an  inter¬ 
nal  resilium. 

Lucina  (Lucina)  bowdenensis,  new  species. 

(Plate  14,  Figures  8,  9.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  thin,  strongly  inflated,  suborbicular;  anterior  dorsal 
margin  short,  slightly  excavated;  upper  part  of  anterior  lateral  margin 
obliquely  truncate;  posterior  dorsal  margin  higher  than  anterior,  longer 
and  slightly  convex;  posterior  lateral  margin  subtruncate  at  dorsal  area; 
umbo  broad,  low;  lunule  very  narrow,  moderately  depressed;  anterior 
dorsal  area  poorly  defined,  posterior  area  more  prominent;  sculpture  con¬ 
sisting  of  numerous  fine,  unequally  spaced  concentric  threads,  becoming 
more  prominent  and  sublamellar  on  the  posterior  area;  between  the  con¬ 
centric  threads  over  the  entire  surface  of  the  shell  are  obscure  wavy  radial 
markings;  hinge  edentulous,  hinge-plate  of  left  valve  swollen  under  umbo, 
simulating  a  cardinal;  hinge  of  right  valve  having  a  corresponding  sub- 
umbonal  depression. 

Length  24.5  mm.;  height  22.2  mm.;  diameter  (left  valve)  6.3  mm. 


112 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


This  species  is  known  from  2  valves.  It  is  more  inequilateral  and 
more  inflated  than  L.  janus  Dali,  a  species  from  the  Chipola  forma¬ 
tion  of  Florida,  and  L.  santarosana  Dali,  a  species  from  the  Oak  Grove 
sand  of  Florida.  It  more  closely  resembles  L.  corpulenta  Dali,  de¬ 
scribed  from  the  Chipola  formation  of  Florida,  but  has  narrower 
umbos  and  a  slightly  depressed  posterior  dorsal  area.  The  Bowden 
species  is  more  inequilateral  than  the  living  West  Indian  species 
L.  chrysostoma  (Meuschen)  and  has  a  more  depressed  posterior  dorsal 
area. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No. 
352805). 

Genus  MYRTAEA  Turton. 

Section  MYRTAEA  s.  s. 

Turton,  1822,  Conchylia  Insularum  Britannicarum,  p.  133. 

Type  (by  monotypy) . — Venus  spinijera  Montagu.  Recent,  seas  of 
Europe. 

The  following  is  a  description  of  the  section  Myrtaea  s.  s. : 

Shell  medium-sized,  elongate  ovate,  subequilateral,  moderately  inflated; 
umbos  low;  lunule  and  escutcheon  long,  narrow,  moderately  depressed; 
sculpture  consisting  of  concentric  lamellae,  prolonged  on  ridge  at  outer 
margin  of  escutcheon;  ligament  and  resilium  long,  narrow;  hinge  of  right 
valve  consisting  of  a  single  cardinal  (3),  and  strong  anterior  and  posterior 
laterals;  hinge  of  left  valve  consisting  of  a  small  anterior  cardinal  (2),  a 
larger  posterior  cardinal  (46),  and  small  anterior  and  posterior  laterals. 

In  America,  Myrtaea  s.  s.  first  appears  in  Eocene  deposits,  but  in 
Europe  no  species  are  known  before  the  Burdigalian.  Living  species 
inhabit  tropical  and  temperate  seas. 

Myrtaea  (Myrtaea)  limoniana  Dali. 

(Plate  14,  Figures  10  to  12.) 

Myrtaea  limoniana  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3, 
part  6,  p.  1358,  plate  52,  fig.  10.  Olsson,  Bull.  Amer.  Paleontology,  vol. 
9,  p.  393,  plate  35,  figs.  11,  23,  1922. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  thin,  subequilateral,  somewhat  longer  than  high,  only 
moderately  convex,  though  hardly  compressed;  beaks  small  and  low;  lunule 
depressed,  narrow,  sublanceolate,  small;  surface  covered  with  fine,  sharp, 
thin,  elevated,  concentric  lamellae,  separated  by  wider  interspaces  and 
more  elevated  near  the  dorsal  margins,  especially  behind  the  beaks,  where 
in  perfect  specimens  5  or  6  of  them  are  produced  as  small  leaflets,  which, 
however,  are  usually  broken  off ;  hinge  with  a  single  right  and  2  left  cardinal 
teeth,  the  laterals  obsolete;  scars  normal;  the  margin  of  the  valves  entire. 
Alt.  8,  Ion.  9,  diam.  4  mm. 

Type  locality. — Bowden,  Jamaica. 

The  largest  valve  measures  11.9  mm.  in  length,  11  mm.  in  height 
and  2.2  mm.  in  diameter.  Some  of  the  valves  are  more  inflated  than 
others.  The  concentric  sculpture  varies  from  slightly  elevated 


PELECYPODS. 


113 


lamellae  to  much  more  conspicuous  lamellar  fringes;  much  of  this 
difference  is,  however,  due  to  erosion.  The  lamellae  are  thin  and 
closely  spaced.  Some  valves  from  which  the  lamellae  have  been  re¬ 
moved  show  microscopic  vermiculations,  like  the  camptonectes  stria- 
tion  of  certain  Pectens,  which  brilliantly  reflect  light. 

The  shells  from  Limon,  Costa  Rica,  are  not  quite  so  large  as  those 
from  Bowden  and  the  concentric  lamellae  are  more  closely  spaced 
than  on  Bowden  shells.  Olsson  records  a  specimen  as  large  as  Bowden 
shells  from  Red  Cliff  Creek,  Costa  Rica.  Despite  the  name,  the  type 
of  this  species  is  from  Bowden. 

M.  limoniana  is  larger  than  M.  lomasdesamba,  a  species  described 
by  Maury  from  the  Cercado  formation  of  the  Dominican  Republic, 
and  has  coarser  sculpture. 

Other  localities. — Gatun  formation  (middle  Miocene),  Costa  Rica. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 

157637). 

Section  MYRTEOPSIS  Sacco. 

Sacco,  1901,  I  Molluschi  dei  Terreni  Terziarii  del  Piemonte  e  della  Liguria, 
part  29,  p.  96. 

Type  (by  original  designation). — Myrteopsis  taurolaevis  Sacco. 
Miocene,  Italy.1 

The  following  is  a  description  of  the  section  Myrteopsis: 

Shell  relatively  large,  elongate  ovate,  inequilateral,  moderately  inflated; 
umbos  low;  lunule  long,  narrow,  slightly  depressed;  escutcheon  absent; 
sculpture  limited  to  irregularly  emphasized  incrementals ;  ligament  and 
resilium  long,  narrow,  deeply  inset;  hinge  of  right  valve  consisting  of  a 
single  cardinal  (3)  and  obscure  anterior  and  posterior  laterals;  hinge  of 
left  valve  consisting  of  a  flattened  anterior  cardinal  (2),  a  narrow  poste¬ 
rior  cardinal  (45),  and  hardly  recognizable  laterals. 

Myrteopsis  is  larger  than  Myrtaea  s.  s.,  and  has  ruder  sculpture  and 
weaker  laterals.  Codakia  ( Jagonia )  pertenera  Dali  seems  to  belong 
to  this  section.  Its  hinge  is  more  like  the  hinge  of  Myrtaea  than  like 
the  hinge  of  Jagonia,  and  externally  the  shell  resembles  Myrteopsis 
magnotaurina  Sacco.  If  this  Bowden  species  is  correctly  placed,  it  is 
the  only  known  Myrteopsis  aside  from  the  Helvetian  species  from  the 
Piedmont  basin  described  by  Sacco. 

Myrtaea  (Myrteopsis)  pertenera  (Dali). 

(Plate  14,  Figures  13  to  16.) 

Codakia  ( Jagonia )  'pertenera  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  6,  p.  1347,  plate  51,  fig.  4. 

The  following  is  the  original  description  of  this  species: 

Shell  rather  large,  very  thin,  with  the  surface  more  or  less  irregularly 

indented,  as  if  from  nestling;  anterior  end  larger,  attenuated,  posterior  end 
- - - - — - % - - — - — — - - - - 

1 1  have  not  seen  the  type  species.  The  description  is  based  on  the  description  and  figures  of 
Myrteopsis  magnotaurina  Sacco. 


114 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


more  plump,  obscurely  vertically  truncate,  beaks  low;  lunule  long  and  very 
narrow,  not  deeply  impressed;  surface  finely,  closely,  concentrically,  and 
radially  striated,  but  so  feebly  that  no  obvious  cancellation  results;  hinge- 
margin  narrow;  hinge-teeth  feeble,  the  laterals  in  the  left  valve  obsolete 
or  absent;  scars  lucinoid;  margins  sometimes  obsoletely  fluted.  Height 
32.5,  length  35.0,  diameter  13.5  mm. 

Type  locality. — Bowden,  Jamaica. 

This  species  has  no  escutcheon.  The  hinge  of  the  right  valve  con¬ 
sists  of  a  single  flattened  cardinal  and  weak  anterior  and  posterior 
laterals.  The  hinge  of  the  left  valve  consists  of  a  small  flattened 
anterior  cardinal  (2),  a  narrow  posterior  cardinal  (4b),  and  mere 
traces  of  laterals.  On  young  valves  the  sculpture  is  more  distinct. 
Apparently  no  similar  American  species  has  been  described. 

Type  material. — 4  cotypes  (U.  S.  Nat.  Mus.  No.  135716). 

Section  EULOPIA  Dali. 

Dali,  1901,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  804. 

Type  (by  original  designation). — Lucina  sagrinata  Dali.  Recent, 
Gulf  of  Mexico. 

The  following  is  a  description  of  the  section  Eulopia: 

Shell  small,  rounded  ovate,  slightly  inequilateral,  strongly  inflated;  lunule 
and  escutcheon  very  narrow,  flattened;  sculpture  consisting  of  thin  con¬ 
centric  lamellae  and  obscure  vermicular  radial  threads  between  the  lamel¬ 
lae;  ligament  and  resilium  external,  deeply  inset;  hinge  of  right  valve  con¬ 
sisting  of  a  large  cardinal  (3)  and  strong  anterior  and  posterior  laterals; 
hinge  of  left  valve  consisting  of  an  anterior  (2)  and  posterior  (46)  cardinal 
and  weak  laterals ;  inner  margin  of  valve  smooth. 

Aside  from  the  difference  in  sculpture,  Eulopia  is  separated  from 
Myrtaea  s.  s.  and  Myrteopsis  by  the  heavier  right  cardinal  (3). 
Eulopia  is  an  American  group  of  Myrtaeas.  The  following  Bowden 
species  are  the  earliest  species: 

Key  to  the  Bowden  species  of  Eidopia. 


Concentric  lamellae  closely  spaced .  M.  ( E .)  vermiculata 

Concentric  lamellae  relatively  distant .  M.  (E.)  furcata 


Myrtaea  (Eulopia)  vermiculata  Dali. 

(Plate  15,  Figures  1  to  3.) 

Myrtaea  ( Eulopia )  vermiculata  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  6,  p.  1359,  plate  52,  fig.  5.  ?  Dali,  1915,  Bull. 

U.  S.  Nat.  Mus.  No.  90,  pp.  136-137,  plate  23,  fig.  14. 

The  following  is  the  original  description  of  this  species: 

Shell  resembling  M.  sagrinata  Dali,  but  shorter  and  more  rounded; 
moderately  convex,  subequilateral,  the  anterior  end  slightly  longer;  beaks 
low  and  inconspicuous,  lunule  narrow,  concavely  excavated;  the  escutcheon 
linear,  longer;  both  bounded  externally  by  a  serrate  carina;  ligamentary 
groove  about  half  as  long  as  the  escutcheon;  surface  with  slightly  elevated, 
thin,  concentric  lamellae,  the  interspaces  radially  sculptured  with  close-set 


PELECYPODS. 


115 


vermiculate  threads;  hinge  with  the  normal  cardinal  dentition  and  distinct 
right  laterals;  adductor  scars  rather  small,  the  interpallial  area  punctate. 
Alt.  6.5,  long.  7.5,  diam.  3.5  mm. 

Type  locality. — Bowden,  Jamaica. 

The  anterior  and  posterior  dorsal  margins  are  of  virtually  the  same 
length.  The  anterior  margin  is  moderately  or  strongly  concave;  the 
posterior  is  slightly  convex  and  slopes  more  steeply. 

The  distinguishing  features  of  this  species  are  the  relatively  distant, 
sharply  raised  concentric  lamellae  and  the  irregular  weak  radials  in 
the  interspaces.  Some  of  the  valves  are  proportionally  wider  than  the 
one  figured  by  Dali.  The  principal  difference  between  this  species 
and  M.  sagrinata  (Dali),  a  living  West  Indian  species,  is  discussed  by 
Dali. 

The  Eulopia  from  the  Tampa  formation  of  Florida  that  wras  referred 
to  this  species  is  no  longer  in  the  National  Museum  collections. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135717). 

Myrtaea  (Eulopia)  furcata  Dali. 

(Plate  15,  Figures  4,  5.) 

Myrtaea  ( Eulopia )  furcata  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  6,  p.  1359,  plate  52,  fig.  13. 

The  following  is  the  original  description  of  this  species: 

Shell  thin,  rounded,  moderately  convex,  subequilateral ;  beaks  low,  incon¬ 
spicuous;  lunule  long  and  narrow,  moderately  impressed,  escutcheon  almost 
linear,  bordered  outwardly  by  a  carina ;  surface  near  the  beaks  with  delicate, 
distant,  slightly  elevated  concentric  lines  which  become  almost  obsolete  over 
the  middle  and  basal  portions  of  the  disk;  radial  sculpture  of  fine,  close-set, 
rather  flattish  threads,  which  towards  the  margins  bifurcate  and  form  a 
rather  widely  divaricate  and  somewhat  irregular  sculpture;  hinge  delicate, 
the  right  laterals  feeble,  ligamentary  groove  distinct,  rather  short;  the 
adductor  scars  large,  normal;  the  margins  of  the  valves  entire.  Alt.  11.5, 
Ion.  13,  diam.  5  mm. 

Type  locality. — Bowden,  Jamaica. 

The  shell  is  broader  than  high ;  the  anterior  dorsal  margin  concave, 
the  posterior  dorsal  margin  straight,  longer,  and  more  steeply  sloping, 
so  that  the  anterior  lateral  margin  is  more  convex  than  the  posterior. 

This  species  is  characterized  by  its  delicate,  widely  spaced  concen¬ 
tric  sculpture,  and  weak  numerous  radials  that  are  rather  abruptly 
bent  upward  at  the  ends  of  the  shell. 

Type  material. — 2  cotypes  (U.  S.  Nat.  Mus.  No.  135714). 

Genus  MILTHA  H.  and  A.  Adams. 

Subgenus  MILTHA  s.  s. 

H.  and  A.  Adams,  1857,  The  Genera  of  Recent  Mollusca,  vol.  2,  p.  468. 

Type  ( by  monotypy). — Lucina  childreni  Gray.  Recent,  Coast  of 
Brazil. 


116 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  following  is  a  description  of  the  subgenus  Miltha  s.  s.: 

Shell  large,  thick,  ovate,  compressed;  umbos  low,  acute;  lunule  very 
small,  deeply  depressed;  anterior  and  posterior  dorsal  areas  poorly  defined; 
sculpture  consisting  of  exaggerated  incrementals  and  obscure  traces  of 
.radials;  ligament  and  resilium  external,  wide,  long;  hinge  of  right  valve 
consisting  of  a  narrow  anterior  cardinal  (3a)  and  a  heavy  obscurely  bifid 
middle  cardinal  (36) ;  hinge  of  left  valve  consisting  of  a  heavy  obscurely 
bifid  anterior  cardinal  (2)  and  a  narrow  posterior  cardinal  (46) ;  anterior 
adductor  scar  very  long. 

There  are  only  four  living  species  of  Miltha  s.  s. ;  one  on  the  coast 
of  Brazil,  two  on  the  Pacific  coast  of  Central  America  and  Mexico, 
and  one  in  the  Indian  Ocean.  Its  Tertiary  distribution  was  more 
extensive.  There  are  American  Tertiary  species  beginning  in  the 
Eocene  and  several  European  species  beginning  in  the  Oligocene.  No 
species  are  known  in  the  Bowden  formation. 

Subgenus  MEGAXINUS  Brugnone. 

Brugnone,  1880,  Bulletino  della  Societa  Malacologica  Italiana,  vol.  6,  p.  146. 

Type  (by  monotypy). — Lucina  rostrata  Pecchioli  (=Lucina  ellip- 
tica  Borson).  Miocene  and  Pliocene,  Italy.1 

The  following  is  a  description  of  the  subgenus  Megaxinus : 

Shell  medium-sized,  subovate,  height  exceeding  length,  or  suborbicular, 
moderately  inflated,  inequilateral;  umbos  low;  lunule  small,  deeply  de¬ 
pressed;  anterior  and  posterior  dorsal  areas  poorly  defined  or  absent; 
sculpture  consisting  of  exaggerated  incrementals;  ligament  seated  on  a 
slender  nymph,  dorsal  margin  of  shell  not  abruptly  indented  at  posterior 
end  of  nymph ;  hinge  edentulous ;  anterior  adductor  scar  moderately  long. 

The  interior  of  most  of  the  specimens  of  the  Bowden  species  pro¬ 
visionally  referred  to  this  subgenus  is  inaccessible.  It  is  more  orbicu¬ 
lar  than  the  type,  thus  resembling  Miltha  ( Megaxinus )  bellardiana 
(Mayer)  and  M.  (M.)  incrassata  (Dubois),  Miocene  species  from 
southern  Europe.  There  seems  to  be  no  generic  difference  between 
these  species  and  the  American  later  Tertiary  and  living  species  called 
Pseudomiltha,  such  as  “Pseudomiltha”  anodonta  (Say).  The  type  of 
Pseudomiltha,  P.  gigantea  (Deshayes),  an  Eocene  species  from  the 
Paris  Basin,  has  a  similar  outline  and  edentulous  hinge,  but  its  wide, 
more  exterior  ligament  is  seated  on  a  heavy  nymph  that  abruptly 
ends  at  the  posterior  end  of  the  ligament,  leaving  a  notch  in  the  dorsal 
margin  of  the  shell  as  viewed  from  above. 

Dali  considered  Megaxinus  as  similar  to  the  genus  Thyasira 
Lamarck.  The  type  of  Thyasira,  Lucina  flexuosa  Montagu,  has  a 
small  thin  shell,  wide  shallow  lunule,  long  narrow  escutcheon,  promi¬ 
nent  posterior  dorsal  area,  less  deeply  inset  ligament,  and  a  false  tooth 
in  front  of  the  umbo,  due  to  the  indentation  of  the  hinge  margin. 

1 1  have  not  seen  the  type  species.  The  description  is  based  on  the  description  and  figures  of 
the  type  given  by  Sacco  and  on  specimens  of  Lucina  incrassata  subscopularum  d’Orbigny  from 
Aquitaine. 


PELECYPODS. 


117 


Miltha  (Megaxinus)  gluminda,  new  species. 

(Plate  15,  Figure  6.) 

The  following  is  a  description  of  this  species: 

Shell  large,  relatively  thin,  suborbicular,  moderately  inflated;  dorsal 
margins  subequal,  diverging  at  an  angle  of  about  120°,  rounding  into  the 
lateral  margins;  umbo  low,  flat;  sculpture  consisting  of  exagerated  in¬ 
cremental;  obscure  radial  threads  are  visible  on  worn  parts  of  the  shell; 
ligament  long,  deeply  inset. 

Length  42.5  mm. ;  height  42  mm. ;  diameter  (right  valve)  11  mm. 

M.  gluminda  is  described  from  several  broken  valves.  A  restored 
fragment  has  approximately  the  following  dimensions:  length  65 
mm.;  height  60  mm.;  diameter  (right  valve)  15  mm. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352807). 

Genus  PHACOIDES  Blainville. 

Subgenus  PHACOIDES  s.  s. 

Blainville,  1825,  Manuel  de  Malacologie  et  de  Conchyliologie,  p.  550. 

Type  ( by  monotypy). — Lucina  jamaicensis  Lamarck  ( =  Tellina 
pectinata  Gmelin).  Recent,  West  Indies. 

The  following  is  a  description  of  the  subgenus  Phacoides  s.  s. : 

Shell  large,  suborbicular,  moderately  inflated;  umbos  low;  lunule  short, 
narrow,  deeply  depressed;  anterior  and  posterior  areas  conspicuous; 
sculpture  consisting  of  concentric  lamellae  and  fine  concentric  threads; 
ligament  and  resilium  external;  hinge  of  right  valve  consisting  of  a  heavy 
flattened  middle  cardinal  (3a),  a  narrow  obscure  posterior  cardinal  (3b), 
and  strong,  thick  anterior  and  posterior  laterals ;  hinge  of  left  valve  consist¬ 
ing  of  narrow  anterior  (2)  and  posterior  (4b)  cardinals,  and  thick  double 
laterals  inclosing  deep  sockets;  anterior  adductor  scar  long,  narrow,  par¬ 
alleling  the  pallial  line;  inner  margin  of  valve  smooth. 

Species  of  Phacoides  s.  s.  occur  in  the  Tertiary  deposits  of  Europe 
and  America.  They  are  found,  like  the  living  species,  in  both  tem¬ 
perate  and  tropical  faunas. 

Phacoides  (Phacoides  ?)  species. 

(Plate  15,  Figure  7.) 

Phacoides  domingensis  Dali  (part),  1903,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  6,  p.  1363,  not  plate  50,  fig.  11. 

The  U.  S.  National  Museum  collection  contains  a  fragment  of  the 
lower  part  of  a  right  valve  of  a  Phacoides  that  probably  is  a  Pha¬ 
coides  s.  s.  The  fragment  shows  part  of  the  posterior  dorsal  area.  The 
sculpture  consists  of  closely  spaced  concentric  lamellae  and  obscure 
secondary  concentric  threads. 

The  type  of  Phacoides  domingensis  is  a  shell  collected  from  beds  of 
unknown  age  on  an  island  in  Lago  de  Henriquillo,  Dominican  Repub¬ 
lic.  The  broken  Bowden  valve  has  more  closely  spaced  concentric 
lamellae  and  less  distinct  secondary  concentric  threads. 


118 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  species  from  the  Tampa  formation  of  Florida  that  has  been 
called  P.  domingensis  apparently  is  not  a  Phacoides  s.  s.,  as  it  has 
radial  sculpture  in  addition  to  the  concentric  sculpture,  and  the  right 
valve  has  double  laterals. 

Subgenus  LINGA  de  Gregorio. 

Section  LINGA  s.  s. 

de  Gregorio,  1884,  Bulletino  della  Societa  Malacologica  Italiana,  vol.  10,  p.  217. 

Type. — Lucina  columbella  Lamarck.  Miocene,  Touraine,  France. 

The  following  is  a  description  of  the  section  Linga  s.  s.: 

Shell  medium-sized,  heavy,  subspherical ;  lunule  small,  cordate,  slightly 
depressed;  anterior  and  posterior  dorsal  areas  very  prominent;  sculpture 
consisting  of  concentric  lamellae;  ligament  and  resilium  external;  hinge  of 
right  valve  consisting  of  a  small  anterior  cardinal  (3a),  heavy  obscurely 
bifid  middle  cardinal  (36),  and  heavy  anterior  and  posterior  laterals  that 
are  indented  on  the  lower  surface,  the  posterior  lateral  much  farther  from 
the  cardinals  than  the  anterior;  hinge  of  left  valve  consisting  of  a  heavy 
obscurely  bifid  anterior  cardinal  (2),  a  smaller  posterior  cardinal  (46), 
and  thick  double  laterals  inclosing  deep  sockets,  the  lower  lamellae  fitting 
into  the  indentations  on  the  lower  surface  of  the  right  laterals;  anterior 
adductor  scar  long  and  narrow,  paralleling  the  pallial  line;  inner  margin 
of  valve  obscurely  wrinkled. 

West  Indian  and  eastern  American  Tertiary  and  living  species  of 
Linga  have  been  placed  in  the  subgenus  Here  Gabb.  The  type  of 
Here ,  Lucina  {Here)  richthofeni  Gabb,  was  described  from  beds  of 
Pliocene  age  in  southern  California.  It  has  a  very  obscure  anterior 
dorsal  area  and  an  extraordinarily  deep  lunule  that  almost  completely 
effaces  the  anterior  cardinal  on  both  valves.  The  upper  laterals  on 
the  left  valve  are  heavy  and  the  lower  surface  of  the  right  laterals  are 
only  slightly  indented.  No  species  similar  to  Phacoides  {Here)  rich - 
thojeni  is  known  from  the  east  coast  of  America  or  the  West  Indies. 

The  earliest  Linga  is  a  species  from  American  middle  Eocene  de¬ 
posits  (Claiborne  group).  Linga  is  particularly  abundant  in  the 
tropical  and  subtropical  late  Tertiary  faunas  of  Florida  and  the  West 
Indies  and  is  still  living  in  the  same  regions.  During  late  Miocene 
time  it  extended  as  far  north  as  North  Carolina,  where,  in  company 
with  many  other  tropical  genera,  it  is  found  in  the  warm  temperate 
fauna  of  the  Duplin  marl.  The  earliest  European  species  is  of  Aqui- 
tanian  age.  Like  many  other  tropical  genera  that  lived  in  European 
seas  during  Miocene  time,  it  has  withdrawn  to  tropical  west  African 
waters. 

Key  to  the  Bowden  species  of  Linga. 

Length  of  adult  shell  exceeding  8  mm.,  concentric  lamellae  not  elevated. 

Shell  strongly  inflated .  P.  (L.)  podagrinus  podagrinus 

Shell  moderately  inflated. 

Posterior  margin  rounded .  P.  (L.)  podagrinus  alarantus 

Posterior  margin  subangular . P.  ( L .)  browni 

Length  of  adult  shell  not  exceeding  8  mm.,  concentric  lamellae  elevated . .  P.  (L.)  tithonis 


PELECYPODS. 


119 


Phacoides  (Linga)  podagrinus  podagrinus  Dali. 

(Plate  15,  Figures  8  to  11.) 

Lucina  pennsylvanica  Guppy  (not  Linne),  Quart.  Jour.  Geol.  Soc.  London, 
vol.  22,  p.  292.  Guppy  (part,  not  Linne),  1874,  Geol.  Mag.,  decade  2, 
vol.  1,  p.  442,  (list). 

Phacoides  (Here)  podagrinus  Dali,  1903,  Tians.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  6,  pp.  1365-1366,  plate  50,  figs.  12,  13. 

The  following  is  the  original  description  of  this  subspecies: 

Shell  when  young  moderately  convex,  when  senile  having  an  exaggerated 
thickness  and  almost  spherical  convexity.  It  belongs  to  the  group  of  P. 
pennsylvanicus  L.,  of  which  species  it  is  doubtless  a  precursor,  and  the 
mention  of  that  species  by  Gabb  and  Guppy  in  the  “Miocene”  (Oligocene) 
of  St.  Domingo  and  Jamaica  doubtless  refers  to  the  present  fossil.  For 
this  reason  it  is  best  described  by  comparison  with  P.  pennsylvanicus ,  from 
which  it  differs  by  its  smaller  size  and  greater  inflation  at  maturity,  its 
finer  and  closer  concentric  sculpture,  its  shorter  and  broader  posterior 
dorsal  area,  its  less  elevated  beaks,  its  slightly  smaller  and  more  distinctly 
limited  anterior  dorsal  area,  and  its  more  nearly  circular  outline.  Alt.  28, 
Ion.  28,  diam.  30  mm.  The  largest  specimen  observed  has  a  length  of  42 
and  a  diameter  of  35  mm.,  while  a  specimen  of  P.  pennsylvanicus  of  the 
same  size  has  a  diameter  of  only  25. 

Type  locality. — Bowden,  Jamaica. 

Although  this  species  is  represented  by  a  large  number  of  shells, 
there  is  a  sharp  break  between  the  few  excessively  inflated  largest 
shells  and  the  smaller  less  inflated  shells.  The  largest  of  the  normal 
shells  has  the  following  dimensions:  length  28  mm.;  height  28  mm.; 
diameter  (right  valve)  10  mm.  The  smallest  of  the  greatly  inflated 
shells  has  the  following  dimensions:  length  32  mm.,  height  33.5  mm., 
diameter  (right  valve)  15  mm.  Dali  figured  one  of  the  greatly  inflated 
shells.  Young  shells  have  higher  umbos  than  adults.  The  strong 
inflation  of  even  normal  shells  and  the  rather  fine  concentric  lamellae 
are  the  characteristic  features  of  this  species.  The  species  from  the 
Tampa  formation  of  Florida,  P.  ivacissanus  Dali,  is  smaller,  less 
inflated  and  has  a  steeper  and  longer  anterior  dorsal  margin.  P.  glenni 
Dali,  described  from  the  Chipola  formation  of  Florida,  is  less  inflated, 
and  has  smaller  umbos  and  coarser  concentric  sculpture.  P.  densatus 
(Conrad),  a  species  from  the  Duplin  marl  of  North  Carolina,  also  is 
less  inflated,  larger  and  has  lower  umbos  than  normal  Bowden  shells. 

A  similar  undescribed  species  was  collected  from  the  Cercado  for¬ 
mation  in  the  Dominican  Republic. 

Type  material. — 7  cotypes  (U.  S.  Nat.  Mus.  No.  135710). 

Phacoides  (Linga)  podagrinus  alarantus,  new  subspecies. 

(Plate  15,  Figure  12.) 

The  following  is  a  description  of  this  subspecies: 

Shell  medium-sized,  suborbicular,  moderately  inflated;  dorsal  areas  con¬ 
spicuous;  lunule  small,  hardly  differentiated  from  the  anterior  dorsal  area; 


120 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


umbos  moderately  inflated;  sculpture  consisting  of  closely  spaced  con¬ 
centric  lamellae. 

Length  26.5  mm.;  height  27.5  mm.;  diameter  (right  valve)  8  mm. 

This  subspecies  is  much  less  inflated  than  P.  podagrinus  prodag- 
rinus,  and  has  a  slightly  wider  anterior  dorsal  area. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352808). 

Phacoides  (Linga)  browni,  new  species. 

(Plate  16,  Figure  1.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  moderately  inflated,  suborbicular;'  posterior  dorsal 
margin  long  and  only  slightly  curved;  posterior  lateral  margin  obscurely 
truncated;  anterior  dorsal  margin  sloping  very  gently;  umbos  low;  poste¬ 
rior  dorsal  area  wide,  not  deeply  depressed;  anterior  dorsal  area  sharply 
depressed;  sculpture  consisting  of  prominent,  evenly  spaced  concentric 
lamellae  over  the  entire  surface  of  the  shell. 

Length  37  mm.;  height  35.5  mm.;  diameter  (left  valve)  9.5  mm. 

P.  browni  is  characterized  by  its  gently  curved  posterior  dorsal 
margin,  low  umbo,  and  prominent  uniform  concentric  sculpture.  It 
is  less  inflated  than  P.  podagrinus  and  has  a  more  angular  posterior 
margin.  It  more  closely  resembles  the  living  West  Indian  species 
P.  pennsylvanicus  (Linne),  but  is  less  inflated,  less  orbicular,  and  has 
a  shorter  anterior  dorsal  margin  and  finer  sculpture. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352809). 

Phacoides  (Linga)  tithonis  Dali. 

(Plate  16,  Figures  2,  3.) 

Phacoides  ( Here )  tithonis  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  6,  pp.  1366-1367,  plate  50,  fig.  10. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  rotund,  with  rather  prominent  beaks,  the  dorsal  areas  not 
distinguished  by  sculpture  and  indicated  only  by  faint,  broad,  radial  sulci; 
lunule  small  and  deep,  no  escutcheon  visible;  surface  with  profuse,  elevated, 
rather  unevenly  spaced,  concentric  lamellae;  hinge  well  developed;  margins 
minutely  crenulated.  Alt.  3.0,  Ion.  4.5,  diam.  3.8  mm. 

Type  locality. — Bowden,  Jamaica. 

The  hinge  of  this  species  resembles  the  hinge  of  the  type  of  Linga , 
but  the  dorsal  areas  are  not  depressed  and  the  concentric  lamellae  are 
thinner  and  more  elevated.  It  resembles,  as  Dali  pointed  out,  the 
living  West  Indian  P.  sombrerensis  Dali. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135723). 

Section  PLEUROLUCINA  Dali. 

Dali,  1901,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  805. 

Type  {by  original  designation) . — Lucina  leucocyma  Dali.  Recent, 
West  Indies. 


PELECYPODS. 


121 


The  following  is  a  description  of  the  section  Pleurolucina: 

Shell  small,  higher  than  wide,  strongly  inflated;  umbos  high,  strongly 
twisted;  lunule  small,  hardly  differentiated;  anterior  and  posterior  dorsal 
areas  prominent,  elevated  near  margin  of  shell;  sculpture  consisting  of  con¬ 
centric  lamellae  and  3  radial  grooves;  ligament  and  resilium  external, 
short;  hinge  of  right  valve  consisting  of  a  small  anterior  cardinal  (3a),  a 
heavy  obsurely  bifid  middle  cardinal  (36),  and  strong  anterior  and  pos¬ 
terior  laterals,  their  lower  surface  indented;  hinge  of  left  valve  consisting 
of  an  obscurely  bifid  anterior  cardinal  (2),  a  posterior  cardinal  (46),  and 
heavy  double  laterals,  the  lower  laterals  larger  than  the  upper;  inner 
margin  of  valve  minutely  fluted. 

The  difference  in  outline  and  sculpture  separate  the  small  species 
of  this  section  from  Linga  s.  s.  The  lucinoid  described  by  Sacco  as 
Here  miobarbieri,  from  the  Helvetian  of  the  Piedmont  basin,  prob¬ 
ably  is  a  Pleurolucina.  If  so,  it  is  the  only  European  representative 
of  this  tropical  American  group.  The  following  Bowden  species  is  the 
earliest  American  species. 

Phacoides  (Pleurolucina)  quadricostatus  Dali. 

(Plate  16,  Figures  4  to  6.) 

Phacoides  ( Pleurolucina )  quadricostatus  Dali,  1903,  Trans.  Wagner  Free  Inst. 
Sci.  Philadelphia,  vol.  3,  part  6,  p.  1368,  plate  50,  fig.  7. 

The  following  is  the  original  description  of  this  species : 

Shell  small,  plump,  oblique,  high,  short,  with  strongly  impressed  large 
dorsal  areas;  beaks  small,  prosogyrate,  overhanging  a  very  small  cavernous 
lunule;  ligament  short;  surface  densely  covered  with  high,  concentric 
lamellae  with  slightly  wider  interspaces,  the  distal  edges  of  the  lamellae 
wider  and  reflexed  dorsally;  radial  sculpture  of  4  rapidly  distally  widening 
broad  ribs  separated  by  narrow  sulci,  the  2  inner  ribs  wider  than  the  outer 
pair;  hinge  normal,  strong;  scars  normal;  inner  margins  of  the  valves 
crenate.  Alt.  9,  Ion.  6,  diam.  7  mm. 

Type  locality. — Bowden,  Jamaica. 

P.  quadricostatus,  the  Pliocene  species  P.  amabilis  Dali  and  the 
living  West  Indian  species  P.  leucocyma  Dali  are  very  similar.  The 
Pliocene  species  is  larger  than  P.  quadricostatus  and  has  finer  and  less 
lamellar  sculpture.  P.  leucocyma  has  less  sharply  defined  radial 
grooves  and  less  lamellar  concentric  sculpture. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135722). 

Subgenus  CARDIOLUCINA  Sacco. 

Sacco,  1901,  I  Molluschi  dei  Terreni  Terziarii  del  Piemonte  e  della  Liguria, 
part  29,  p.  89. 

Type  {by  original  designation). — Cardium  agassizii  Michelotti. 
Miocene,  Italy.1 

The  following  is  a  description  of  the  subgenus  Cardiolucina: 

Shell  small,  strongly  inflated,  strongly  inequilateral,  anterior  end  ex¬ 
tended;  lunule  small,  deeply  depressed;  anterior  and  posterior  dorsal  areas 

U  have  not  seen  the  type  species.  The  description  is  based  on  the  description  and  figures  given 
by  Sacco. 


122 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


slightly  depressed;  sculpture  consisting  of  concentric  lamellae  frilled  by 
obscure  threads;  ligament  and  resilium  external;  hinge  of  right  valve  con¬ 
sisting  of  a  very  small  anterior  cardinal  (3a),  a  heavier  middle  cardinal 
(36),  and  strong  anterior  and  posterior  laterals;  hinge  of  left  valve  con¬ 
sisting  of  an  anterior  cardinal  (2),  a  smaller  posterior  cardinal  (46),  and 
double  anterior  and  posterior  laterals,  the  lower  laterals  stronger  than  the 
upper;  inner  margin  of  valve  minutely  frilled. 

The  American  Tertiary  and  living  species  of  Cardiolucina  have  been 
placed  in  the  subgenus  Cavilucina  Fischer.  The  type  of  Cavilucina, 
Lucina  salcata  Lamarck,  described  from  Eocene  beds  in  the  Paris 
Basin,  has  very  obscure  cardinals  and  laterals. 

Cossmann  suggested  that  the  Eocene  species  Lucina  barbieri 
Deshayes  probably  is  a  Cardiolucina.  The  oldest  American  species 
are  of  lower  Miocene  (Burdigalian)  age.  There  are  many  species  in 
the  Miocene  and  Pliocene  tropical  and  subtropical  American  faunas. 
The  group  is  now  living  in  West  Indian  waters,  but  has  completely 
disappeared  in  European  waters. 

Phacoides  (Cardiolucina)  recurrens  Dali. 

(Plate  16,  Figures  7,  8.) 

Phacoides  ( Cavilucina )  recurrens  Dali  (part),  1903,  Trans.  Wagner  Free  Inst. 
Sci.  Philadelphia,  vol.  3,  part  6,  p.  1369,  plate  52,  fig.  11.  Dali  (part), 
1915,  Bull.  U.  S.  Nat.  Mus.,  No.  90,  p.  138,  plate  24,  fig.  3. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  flattish  or  only  moderately  convex,  oblique,  inequilateral, 
the  dorsal  areas  hardly  indicated;  beaks  small,  low,  prosogyrate  over  a 
small,  moderately  impressed  rather  narrow  lunule;  posterior  dorsal  margin 
convexly  arched,  as  high  as  the  beaks;  surface  finely,  concentrically 
rather  closely  grooved,  with,  toward  the  base,  2  or  3  deep,  concentric  sulci 
indicating  resting  stages;  hinge-teeth  small  but  distinct;  inner  margins  of 
the  valves  minutely  crenulated.  Alt.  6.5,  Ion.  5.7,  diam.  4.0  mm. 

Type  locality. — Bowden,  Jamaica. 

This  species  is  conspicuous  for  its  small  size,  very  inequilateral  out¬ 
line  and  prominent  umbos.  The  fine  concentric  sculpture  is  obscure 
or  entirely  absent  on  many  shells  and  the  surface  is  almost  smooth 
except  for  the  deep  irregularly  spaced  grooves. 

No  specimens  of  this  species  from  the  Tampa  formation  of  Florida 
are  in  the  U.  S.  National  Museum  collection  at  the  present  time.  The 
shell  figured  in  Bulletin  90  of  the  U.  S.  National  Museum  is  the  type, 
a  Bowden  shell.  Specimens  from  the  Chipola  formation  of  Florida 
formerly  called  P.  recurrens  have  been  referred  by  Gardner  to  P.  tris - 
culcatus  (Conrad),  a  Duplin  marl  species  that  has  wider  and  fuller 
umbos  and  a  larger  lunule. 

Similar  small  Cardiolucinas  are  common  in  the  Miocene  and  Plio¬ 
cene  deposits  of  Florida  and  the  middle  Atlantic  states.  Such  species 
include  P.  trisulcatus  (Conrad),  P.  multistriatus  (Conrad),  P.  whit- 


PELECYPODS. 


123 


fieldi  Dali,  and  the  living  P.  blandus  Dali.  None  of  the  American 
species  have  the  radial  sculpture  of  the  type  species,  but  they  have  a 
minutely  frilled  inner  margin  and  the  same  type  of  hinge. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135721). 

Subgenus  CALLU CIN A  Dali. 

Dali,  1901,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  806. 

Type  {by  original  designation) . — Lucina  radians  Conrad.  Miocene 
and  Pliocene,  middle  Atlantic  States. 

The  following  is  a  description  of  the  subgenus  Callucina: 

Shell  medium-sized,  suborbicular,  moderately  inflated;  lunule  larger  on 
left  valve  than  on  right;  dorsal  areas  absent;  sculpture  consisting  of  con¬ 
centric  lamellae  and  obscure  radial  threads;  ligament  and  resilium  ex¬ 
ternal;  hinge  of  right  valve  consisting  of  a  bifid  midle  cardinal  (3),  and 
obscure  traces  of  laterals;  hinge  of  left  valve  consisting  of  anterior  (2)  and 
posterior  (46)  cardinals,  and  obscure  traces  of  laterals;  inner  margin  of 
valve  finely  fluted. 

Callucina  resembles  Cavilucina  Fischer,  but  has  stronger  cardinals. 
All  the  Tertiary  and  living  species  of  Callucina  are  American.  They 
first  appear  in  middle  Miocene  deposits  and  are  characteristic  of 
tropical  and  subtropical  faunas. 

Key  to  the  Bowden  species  of  Callucina. 

Radial  sculpture  obscure,  length  of  adult  shell  exceeding  10  mm _ P.  (C.)  pauperatus 

Concentric  sculpture  consisting  of  fine  lamellae _ P.  (C.)  pauperatus  pauperatus 

Concentric  sculpture  consisting  of  relatively  coarse  lamellae. 

P.  ( C .)  pauperatus  oligocostatus 

Radial  sculpture  relatively  strong,  length  of  adult  shell  not  exceeding 

10  mm .  P.  (C.)  eurycostatus 

Phacoides  (Callucina)  pauperatus  pauperatus  (Guppy). 

(Plate  16,  Figures  9  to  13.) 

Lucina  pauperata  Guppy,  in  Guppy  and  Dali,  1896,  Proc.  U.  S.  Nat.  Mus., 
vol.  19,  p.  326,  plate  30  fig.  3. 

Phacoides  ( Callucina )  pauperatus  (Guppy),  Dali,  1903,  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  6,  p.  1380. 

The  following  is  the  original  description  of  this  subspecies: 

Suborbicular,  not  very  convex,  with  faint,  broad  radiating  (ray-like) 
grooves  and  sublamellar  concentric  ridges.  Diameter,  11.5  mm.  The 
radiating  ornament  looks  like  color,  but  it  is  really  faint,  shallow  flutings. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  sub¬ 
species  : 

Shell  medium-sized,  moderately  inflated,  suborbicular,  anterior  end 
slightly  more  extended;  posterior  margin  almost  vertically  subtruncate; 
umbos  full,  low;  anterior  and  posterior  dorsal  areas  poorly  defined;  lunule 
narrow,  shallow,  of  variable  length,  absent  or  poorly  developed  on  some 
left  valves;  sculpture  consisting  of  fine,  closely  spaced  concentric  lamellae, 


124 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


which  are  sharp-edged  toward  the  margins  and  on  many  adult  shells  are 
absent  on  the  upper  median  part  of  shell;  very  obscure  radial  threads  and 
wider  depressions  of  varying  width  radiate  from  the  umbo;  inner  margin 
of  the  valve  finely  fluted. 

Length  16.5  mm.;  height  16.5  mm.;  diameter  (right  valve)  3.8  mm. 

This  is  one  of  the  most  abundant  Lucinoid.  The  largest  valve  has 
the  following  dimensions:  length  18.5  mm.;  height  18  mm.;  diameter 
4.6  mm.  The  radials  are  weak,  but  on  some  shells  undulate  the  con¬ 
centric  lamellae.  In  addition  to  these  relatively  coarse  radials,  very 
fine  and  obscure  radials  may  cover  the  median  part  of  adult  shells. 

Young  valves  that  have  obscure  radials  and  strong  concentric  sculp¬ 
ture  may  be  confused  with  specimens  of  Myrtaea  limoniana  of  the 
same  size  and  this  resemblance  is  augmented  by  the  similarity  of  the 
hinge.  P.  pauperatus  is  slightly  more  convex,  and  has  more  promi¬ 
nent  umbos  and  a  stronger  hinge.  The  fluting  of  the  inner  margin  of 
P.  pauperatus,  which  on  most  young  valves  is  more  prominent  than 
on  adults,  is  an  infallible  guide. 

P.  radians  (Conrad),  which  ranges  from  the  Duplin  marl  (upper 
Miocene)  to  the  Recent,  closely  resembles  the  Bowden  species,  but  is 
slightly  more  inflated,  and  has  higher,  narrower,  and  more  strongly 
twisted  umbos,  stronger  sculpture,  and  heavier  hinge.  Olsson  has 
described  a  small  Miocene  subspecies,  P.  radians  medioamericanus 
from  Costa  Rica. 

Type  material. — 2  cotypes  (U.  S.  Nat.  Mus.  No.  107101). 

Phacoides  (Callucina)  pauperatus  oligocostatus,  new  subspecies. 

(Plate  16,  Figures  14,  15.) 

The  following  is  a  description  of  this  subspecies: 

Shell  medium-sized,  suborbicular,  strongly  inflated;  umbos  full,  relatively 
high;  dorsal  area  not  differentiated;  concentric  sculpture  consisting  of  coarse, 
strong  lamellae ;  radial  sculpture  consisting  of  very  obscure  threads. 

Length  17.8  mm. ;  height  16.8  mm. ;  diameter  (right  valve)  4.5  mm. 

This  subspecies  is  more  orbicular  and  more  inflated  than  P.  pau¬ 
peratus  pauperatus  and  has  more  obscure  dorsal  areas  and  coarser, 
more  persistent  concentric  sculpture.  Externally,  it  resembles  Pha¬ 
coides  perplexus  Pilsbry  and  Johnson,  a  Miocene  species  from  the 
Dominican  Republic,  but  has  narrower  ribs  on  the  umbo;  it  also  has 
more  slender  cardinals  on  the  left  valve. 

Type  material. — ILolotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352810). 

Phacoides  (Callucina)  eurycostatus,  new  species. 

(Plate  16,  Figures  16,  17.) 

The  following  is  a  description  of  this  species: 

Shell  small,  inflated,  suborbicular;  anterior  dorsal  margin  short,  deeply 
excavated;  posterior  margin  subtruncate;  umbo  full,  narrow,  relatively 
high;  lunule  cordate,  deeply  depressed;  dorsal  areas  obscure;  sculpture 


PELECYPODS. 


125 


consisting  of  relatively  broad  obscure  radials,  and  fine,  closely  and  evenly 
spaced,  low  concentric  lamellae,  poorly  defined  in  the  median  dorsal  region; 
inner  margin  of  valve  bearing  obsure,  fine  flutings  and  broader  undulations 
that  conform  to  the  external  radials;  right  valve  not  known. 

Length  8  mm.;  height  7.5  mm.;  diameter  (left  valve)  1.8  mm. 

This  species  is  known  only  from  the  holotype,  a  left  valve.  It  is 
distinguished  from  young  shells  of  P.  pauperatus  by  its  greater  infla¬ 
tion,  deeper  lunule,  and  much  broader,  more  pronounced  radials. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352811). 

Subgenus  PARVILUCINA  Dali. 

Section  PARVILUCINA  s.  s. 

Dali,  1901,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  806. 

Type  (by  original  designation). — Lucina  tenuisculpta  Carpenter. 
Recent,  west  coast  of  United  States. 

The  following  is  a  description  of  the  section  Parvilucina  s.  s.: 

Shell  small,  suborbicular,  slightly  inequilateral;  lunule  small,  deeply  de¬ 
pressed;  dorsal  areas  absent;  sculpture  consisting  of  concentric  lamellae 
and  low  radial  threads;  ligament  and  resilium  external;  hinge  of  right 
valve  consisting  of  an  obscurely  bifid  middle  cardinal  (3)  and  strong 
laterals;  hinge  of  left  valve  consisting  of  anterior  (2)  and  posterior  (45) 
cardinals  and  double  laterals;  inner  margin  of  valve  minutely  fluted. 

Parvilucina  is  separated  from  Callucina  by  the  strong  laterals  and 
stronger  sculpture.  It  resembles  Cardiolucina,  but  has  no  right  ante¬ 
rior  cardinal.  It  is  another  American  group  of  small  Phacoides  first 
appearing  in  middle  Eocene  deposits.  Species  have  been  described 
from  the  temperate  Miocene  faunas  of  the  Atlantic  states,  as  well  as 
from  the  southern  tropical  and  subtropical  faunas. 

Key  to  the  Bowden  species  of  Parvilucina  s.  s. 

Shell  moderately  inflated,  radial  sculpture  weak . P.  ( P .)  yaquensis  morantensis 

Shell  strongly  inflated,  radial  sculpture  relatively  strong . P.  (P.)  limnidus 

Phacoides  (Parvilucina)  yaquensis  morantensis,  new  subspecies. 

(Plate  17,  Figures  1,  2.) 

Phacoides  ( Parvilucina )  yaquensis  Dali  (part,  not  Gabb),  1903,  Trans. 

Wagner  Free  Inst.  Sci.  ‘Philadelphia,  vol.  3,  part  6,  p.  1382. 

The  following  is  a  description  of  this  subspecies: 

Shell  small,  subequilateral,  moderately  inflated;  anterior  dorsal  margin 
excavated;  posterior  dorsal  margin  almost  straight,  sloping,  meeting  lateral 
margin  at  a  subrounded  angle;  anterior  lateral  margin  longer  and  less 
curved  than  posterior;  base  sloping  toward  anterior  end;  umbos  relatively 
prominent;  lunule  small,  cordate,  moderately  depressed;  sculpture  con¬ 
sisting  of  closely  spaced,  thin,  concentric  lamellae  and  narrow  obscure 
radials,  separated  by  narrower  interspaces;  on  some  shells  the  radials  are 
strong  enough  to  slightly  wrinkle  the  lamellae ;  radials  absent  on  the  dorsal 
areas;  hinge  normal,  laterals,  especially  the  posterior,  elongate;  inner 
margin  of  valve  finely  and  weakly  fluted. 

Length  5.0  mm.;  height  4.5  mm.;  diameter  (right  valve)  1.2  mm. 


126 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


This  subspecies  closely  resembles  P.  yaquensis  yaquensis  Gabb, 
which  is  the  most  common  Lucinoid  in  the  Cercado  formation  of  the 
Dominican  Republic  but  is  slightly  larger,  and  has  more  distinct 
radial  sculpture,  and  deeper  lunule.  The  most  striking  difference  is 
the  heavier  hinge  of  the  Bowden  subspecies. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352812). 

Phacoides  (Parvilucina)  limnidus,  new  species. 

(Plate  17,  Figures  3,  4.) 

The  following  is  a  description  of  this  species: 

Shell  small,  suborbicular,  strongly  inflated;  anterior  margin  more  evenly 
rounded  than  posterior;  umbo  full,  high,  broad;  lunule  relatively  large, 
deeply  depressed;  dorsal  areas  poorly  defined;  sculpture  consisting  of  low 
narrow  radials,  crossed  by  concentric  wrinkles  and  low  lamellae;  hinge  of 
right  valve  consisting  of  a  heavy,  strongly  oblique  middle  cardinal  (3)  and 
anterior  and  posterior  laterals;  inner  margin  of  valve  weakly  fluted;  left 
valve  not  known. 

Length  5.5  mm.;  height  5.5  mm.;  diameter  (right  valve)  2  mm. 

This  species  is  described  from  one  right  valve.  It  is  more  strongly 
inflated  than  P.  yaquensis  morantensis  and  has  cruder  sculpture, 
recalling  Codakia  ( Jagonia )  guppyi. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352813). 

Section  BELLUCINA  Dali. 

Dali,  1901,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  806. 

Type  ( by  original  designation). — Parvilucina  eucosmia  Dali 
( =Lucina  pisum  Reeve  1850,  not  Sowerby,  1837).  Recent,  Indo- 
Pacific.1 

The  following  is  a  description  of  the  section  Bellucina: 

Shell  small,  suborbuicular ;  lunule  moderately  small,  moderately  de¬ 
pressed;  posterior  dorsal  area  strongly  defined;  sculpture  consisting  of 
strong  radials  and  strong  concentric  lamellae ;  hinge  resembling  Parvilucina 
s.  s. ;  inner  margin  of  valve  finely  fluted. 

The  stronger  sculpture  and  stronger  posterior  dorsal  area  separate 
Bellucina  from  Parvilucina  s.  s.  Bellucina  comprises  several  Ameri¬ 
can  and  Pacific  species.  The  following  Bowden  species  is  the  earliest 
species. 

Phacoides  (Bellucina)  actinus  Dali. 

(Plate  17,  Figures  5  to  8.) 

Phacoides  ( Bellucina )  actinus  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  6,  p.  1385,  plate  52,  fig.  3.  Maury,  1917,  Bull. 
Amer.  Paleontology,  vol.  5,  p.  370.  Olsson,  1922,  Bull.  Amer.  ‘Paleon¬ 
tology,  vol.  9,  p.  396,  plate  35,  fig.  24. 


1 1  have  not  seen  the  type  species.  The  description  is  based  on  Dali’s  description  and  on  figures 
of  Lucina  pisum  given  by  Reeve. 


PELECYPODS. 


127 


The  following  is  the  original  description  of  this  species: 

Shell  small,  plump,  somewhat  inequilateral,  with  moderately  prominent, 
slightly  decurved  beaks;  anterior  end  larger  and  more  inflated;  lunule 
lanceolate,  somewhat  longer  and  narrower  in  the  right  valve,  distinctly  im¬ 
pressed;  escutcheon  impressed,  almost  linear;  disk  with  16  to  18  rounded 
radial  ribs,  entire  and  wider  towards  the  base,  with  narrower  deep  inter¬ 
spaces;  concentric  sculpture  of  thin  lamellae,  with  much  wider  interspaces, 
which  are  somewhat  crenulated  or  waved  by  overriding  the  ribs  and  dipping 
into  the  radial  interspaces;  dorsal  areas  large,  slightly  impressed,  with  no 
radial  sculpture,  the  concentric  lamellae  on  the  posterior  area  close-set, 
low,  but  on  the  bounding  rib  and  on  a  radial  line  near  the  dorsal  margin 
slightly  elevated;  hinge  normal,  delicate,  internal  margins  minutely  crenu- 
late.  Alt.  4.5,  Ion.  4.6,  diam.  3.0  mm. 

Type  locality. — Bowden,  Jamaica. 

The  small  valves  of  this  species  are  very  abundant.  The  number 
of  radial  ribs  may  be  as  high  as  22.  The  escutcheon  is  not  so  deeply 
depressed  as  the  lunule  and  the  posterior  dorsal  area  is  more  con¬ 
spicuous  than  the  anterior.  Some  of  the  valves  are  much  more 
inflated  than  others.  The  radial  or  concentric  sculpture,  or  both,  may 
be  weak.  Valves  sculptured  with  suppressed  radials  closely  resemble 
P.  yaquensis  morantensis,  from  which  they  may  be  distinguished  by 
their  coarser  concentric  sculpture,  more  pronounced  posterior  dorsal 
area,  more  deeply  depressed  lunule,  slightly  heavier  hinge,  and  deeper 
and  coarser  internal  fluting. 

Maury  has  described  the  same  or  a  similar  species  from  the  Cercado 
formation  of  the  Dominican  Republic.  Olsson  has  described  small 
specimens  from  Bocas  Island,  Panama. 

Qther  localities. — ?  Cercado  formation  (lower  Miocene),  Dominican 
Republic.  Gatun  formation  (middle  Miocene),  Panama. 

Type  material. — 5  cotypes  (TJ.  S.  Nat.  Mus.  No.  135719). 

Genus  DAVARICELLA  von  Martens. 

Section  DIVARICELLA  s.  s. 

von  Martens,  1880,  Beitrage  zur  Meersfauna  der  Insel  Mauritius  und  der 
Seychellen,  p.  321. 

Type  {by  monotypy) . — Lucina  ( Divaricella )  angulifera  von  Mar¬ 
tens  {=Lucina  ornata  Reeve).  Recent,  Indo-Pacific.* 1 

The  following  is  a  description  of  the  section  Divaricella  s.  s. : 

Shell  medium-sized,  orbicular,  strongly  inflated;  umbos  low;  lunule  small, 
moderately  deep;  sculpture  consisting  of  oblique  grooves  angulated  along 
a  line  extending  obliquely  downward  and  forward  from  the  umbo ;  ligament 
and  resilium  united,  deeply  inset;  hinge  of  right  valve  consisting  of  a  nar¬ 
row  anterior  cardinal  (3a),  a  heavy  middle  cardinal  (36),  and  an  anterior 
and  posterior  lateral;  hinge  of  left  valve  consisting  of  a  heavy  anterior 
cardinal  (2),  a  narrow  posterior  cardinal  (46),  and  double  anterior  and 

posterior  laterals;  posterior  laterals  much  farther  from  cardinals  than 

% 

‘ - 9 - - — - - 

1 1  have  not  seen  the  type  species. 


128 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


anterior;  inner  margin  of  valve  finely  fluted;  anterior  adductor  scar  long 
and  narrow,  paralleling  pallial  line. 

Tertiary  and  living  species  of  Divaricella  have  a  wide  distribution. 

Divaricella  (Divaricella)  prevaricata  Guppy. 

(Plate  17,  Figures  9  to  13.) 

Divaricella  'prevaricata  Guppy,  in  Guppy  and  Dali,  1896,  Proc.  U.  S.  Nat. 
Mus.,  vol.  19,  p.  327,  plate  30,  fig.  4.  Dali,  1903,  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  6,  p.  1389.  ?  Maury,  1920,  Scientific 

Survey  Porto  Rico  and  Virgin  Islands,  vol.  3,  part  1,  p.  34,  New  York 
Acad.  Sci.  ?  Hubbard,  1921,  Scientific  Survey  Porto  Rico  and  Virgin 
Islands,  vol.  3,  part  2,  p.  113,  New  York  Acad.  Sci.  Not  Maury,  1917, 
Bull.  Amer.  Paleontology,  vol.  5,  p.  371,  plate  61,  fig.  10.  (=  D.  proletaria 
Pilsbry  and  Johnson). 

The  following  is  the  original  description  of  this  species: 

Suborbicular,  inflated,  margins  minutely  denticulate,  surface  divaricately 
sculptured.  Length  of  shell,  8  mm. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  medium-sized,  thin,  suborbicular,  moderately  inflated;  posterior 
dorsal  margin  slightly  longer  and  straighter  than  anterior;  umbos  full, 
relatively  prominent;  lunule  small,  slightly  depressed,  almost  or  entirely 
confined  to  right  valve;  sculpture  relatively  fine;  incremental  irregularly 
spaced  and  unequally  emphasized;  right  posterior  cardinal  of  some  valves 
obscurely  bifid;  posterior  and  anterior  laterals  strong;  inner  dorsal  margin 
slightly  serrated  by  the  sculpture,  remainder  of  margin  non-serrate,  but 
finely  fluted  on  its  inner  edge. 

Length  12.5  mm.;  height  12.1  mm.;  diameter  (left  valve)  3.9  mm. 

A  few  valves  have  slightly  coarser  sculpture  than  the  holotype.  It 
is  difficult  to  separate  some  of  the  valves  from  immature  valves  of  the 
living  West  Indian  species  D.  quadrisulcata  (d’Orbigny),  but  the  right 
and  left  anterior  cardinals  of  the  Bowden  species  are  heavier.  The 
species  described  by  Maury  from  the  Cercado  formation  of  the 
Dominican  Republic  as  D.  “ prevaricata”  is  D.  proletaria.  The  Bow¬ 
den  species  has  heavier  anterior  cardinals,  finer  sculpture,  and  lower 
and  less  inflated  umbos.  External  casts  of  a  Divaricella  from  the 
Quebradillas  limestone  (lower  Miocene)  of  Porto  Rico  were  called 
D.  prevaricata  by  Maury  and  Hubbard. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  107102). 

Family  DIPLOD ONTIDAE. 

Genus  DIPLODONTA  Bronn. 

Section  DIPLODONTA  s.  s. 

Bronn,  1831,  Italiens  Tertiar-Gebilde  und  deren  organisch  Einschliisse,  p.  xii. 

Type  (by  subsequent  designation ,  Gray  1847). — Venus  lupina 
Brocchi  ( =  Tellina  rotundata  Montagu).  Miocene  and  Pliocene, 
Italy. 


PELECYPODS. 


129 


The  following  is  a  description  of  the  section  Diplodonta  s.  s.: 

Shell  medium-sized,  suborbicular;  sculpture  consisting  of  incrementals ; 
ligament  external;  hinge  of  right  valve  consisting  of  a  heavy  anterior  car¬ 
dinal  (3a)  and  a  heavy,  deeply  bifid  middle  cardinal  (36) ;  hinge  of  left 
valve  consisting  of  a  heavy  deeply  bifid  anterior  cardinal  (2)  and  a  narrow 
posterior  cardinal  (46) ;  anterior  adductor  scar  longer  and  narrower  than 
posterior. 

Species  of  Diplodonta  s.  s.  were  widely  distributed  in  the  Tertiary 
seas  and  their  present  distribution  is  extensive. 

The  Bowden  species  are  much  smaller  than  the  type  species. 

Key  to  the  Bowden  species  of  Diplodonta  s.  s. 

Shell  suborbicular,  strongly  inflated .  D.  (D.)  walli 

Shell  trigonal,  moderately  inflated .  D.  ( D .)  homalostriata 

Diplodonta  (Diplodonta)  walli,  new  species. 

(Plate  17,  Figures  14,  15.) 

The  following  is  a  description  of  this  species: 

Shell  small,  suborbicular,  strongly  inflated;  anterior  margin  slightly 
more  extended  than  posterior;  umbos  full,  broad,  high;  sculpture  limited 
to  irregularly  spaced,  obscure  incrementals;  hinge  of  right  valve  consisting 
of  2  subequal  cardinals,  the  posterior  one  (36)  obscurely  bifid;  hinge  of  left 
valve  consisting  of  a  long,  bifid  anterior  cardinal  (2)  and  a  narrow  posterior 
cardinal  (46) ;  ligament  short. 

Length  6.5  mm.;  height  6.5  mm.;  diameter  (right  valve)  2.5  mm. 

D.  walli,  which  is  represented  by  2  valves,  externally  resembles 
D.  capuloides  (Gabb),  a  species  confined  to  the  Cercado  formation  of 
the  Dominican  Republic,  but  is  larger  and  has  a  heavier  hinge;  its 
right  anterior  cardinal  (3a)  is  simple,  not  composed  of  two  parts. 
D.  capuloides  apparently  is  not  a  Diplodonta  s.  s.,  but  is  not  a 
Sphaerella,  as  Pilsbry  has  suggested. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352815). 

Diplodonta  (Diplodonta)  homalostriata,  new  species. 

(Plate  17,  Figures  16,  17.) 

The  following  is  a  description  of  this  species: 

Shell  small,  trigonal  suborbicular,  moderately  inflated,  anterior  lend 
slightly  more  extended  than  posterior;  umbos  low,  narrow;  sculpture  con¬ 
sisting  of  fine,  obscure  concentric  rugae;  ligament  short;  hinge  of  right 
valve  consisting  of  a  narrow  anterior  cardinal  (3a),  and  a  heavy  bifid 
posterior  cardinal  (36) ;  hinge  of  left  valve  consisting  of  a  heavy  bifid 
anterior  cardinal  (2)  and  a  narrow  posterior  cardinal  (46). 

Length  6.2  mm.;  height  6.2  mm.;  diameter  (right  valve)  1.5  mm. 

This  species  closely  resembles  D.  collina  Olsson,1  described  from 
Miocene  beds  in  Costa  Rica,  but  is  slightly  less  inflated  and  less 
inequilateral  and  has  wider  umbos. 


1  Comparison  based  on  figures. 


130 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352816). 

Section  FELANIELLA  Dali. 

Dali,  1899,  Journal  of  Conchology,  vol.  9,  p.  244. 

Type  ( by  original  designation). — Felania  usta  Gould.  Recent, 
Japan.1 

The  following  is  a  description  of  the  section  Felaniella: 

Shell  small,  very  inequilateral,  slightly  inflated;  sculpture  consisting  of 
incrementals;  ligament  external;  hinge  of  right  valve  consisting  of  a  nar¬ 
row  anterior  cardinal  (3a)  and  a  heavy,  deeply  bifid  middle  cardinal  (36) ; 
hinge  of  left  valve  consisting  of  a  heavy,  deeply  bifid  anterior  cardinal  (2) 
and  a  narrow  posterior  cardinal  (46). 

The  shell  is  more  compressed  and  more  inequilateral  than  in  Diplo- 
donta  s.  s.  Felaniella  first  appears  in  Eocene  deposits  in  America 
and  Europe.  Although  Miocene  species  are  recorded  from  southern 
Europe,  the  living  species  seem  to  be  confined  to  West  Indian  and 
Pacific  waters. 

Diplodonta  (Felaniella)  minor  Dali. 

(Plate  17,  Figures  18  to  21.) 

Diplodonta  ( Felaniella )  minor  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  5,  p.  1183,  plate  44,  fig.  17. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  moderately  convex,  smooth,  polished,  oblique,  inequilateral, 
the  lower  anterior  side  produced,  the  posterior  side  shorter,  rounded; 
margins  simple,  pallial  line  and  adductor  scars  normal,  the  right  anterior 
cardinal  submarginal,  rather  long;  the  posterior  cardinal  short,  vertical, 
deeply  bifid,  the  beaks  low  and  pointed,  both  the  left  anterior  cardinals 
short,  the  anterior  bifid.  Alt.  4.5,  lat.  3.8,  diam.  2.5  mm. 

Type  locality. — Bowden,  Jamaica. 

The  surface  may  bear  obscure  concentric  striae.  This  species  resem¬ 
bles  the  Miocene  Dominican  species  D.  dedecoris  Pilsbry  and  Johnson 
and  D.  insula  Olsson,  a  Miocene  species  from  Panama,  but  is  more 
oblique. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135724). 

Section  PHYLCTIDERMA  Dali. 

Dali,  1899,  Journal  of  Conchology,  vol.  9,  p.  244. 

Type  {by  original  designation). — Diplodonta  semiaspera  Philippi. 
Recent,  West  Indies. 

The  following  is  a  description  of  the  section  Phlyctiderma: 

Shell  small,  suborbicular,  strongly  inflated;  sculpture  consisting  of  in¬ 
crementals  and  minute  pustules;  ligament  and  resilium  external;  hinge  of 
right  valve  consisting  of  a  relatively  heavy  anterior  cardinal  (3a),  and  a 


1 1  have  not  seen  the  type  species. 


PELECYPODS. 


131 


heavy,  oblique,  bifid  posterior  cardinal  (3b) ;  hinge  of  left  valve  consisting 
of  a  heavy  bifid  anterior  cardinal  (2),  and  a  narrow,  elongate  posterior 
cardinal  (46). 

The  pustular  sculpture  is  the  most  striking  feature  of  this  section, 
which  is  an  American  and  Pacific  group  of  Diplodontas,  first  appear¬ 
ing  in  Miocene  time. 

Diplodonta  (Plyctiderma)  gabbi  Dali. 

(Plate  18,  Figures  1  to  3.) 

Mysia  subquadrata  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.  vol.  15, 
p.  252.  Not  Diplodonta  subquadrata  Carpenter,  1855. 

D.  diplodonta )  gabbi  Dali,  1900,  Trans.  Wagner  Fee  Inst.  Sci.  Philadelphia, 
vol.  3,  part  5,  p.  1183,  footnote. 

Diplodonta  ( Phlyctiderma )  puncturella  Dali,  1900,  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  5,  p.  1183,  plate  45,  fig.  26.  Dali 
and  Simpson,  1901,  Bull.  U.  S.  Fish  Comm.,  vol.  20,  part  1,  p.  495.  Maury, 
1917,  Bull.  Amer.  Paleontology,  vol.  5,  p.  371.  Not  Dali,  1915,  Bull.  U.  S. 
Nat.  Mus.,  No.  90,  p.  140. 

Diplodonta  ( Phlyctiderma )  gabbi  Dali,  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci. 
Philadelphia,  vol.  73,  p.  418,  text-fig.  43. 

The  following  is  the  original  description  of  Mysia  subquadrata 
Gabb : 

Shell  small,  thin,  moderately  convex;  outline  rounded  sub-quadrate, 
length  and  width  about  equal,  beaks  small,  prominent,  hinge-line  sloping 
equally  on  both  sides.  Surface  smooth. 

Type  locality. — Dominican  Republic. 

The  following  description  is  quoted  from  Pilsbry: 

Externally,  this  species  has  an  extremely  minute,  irregular  but  dense 
punctuation.  The  largest  valve  (figured)  measures,  length  5.6,  alt.  5.4, 
diam.  1.65  mm. 

The  following  is  the  original  description  of  D.  puncturella  Dali: 

Shell  small,  thin,  rounded,  moderately  convex,  with  inconspicuous  beaks, 
outline  nearly  circular,  the  beaks  smooth,  but  the  rest  of  the  external  sur¬ 
face  closely  minutely  punctate  all  over,  other  characters  as  in  typical 
Diplodonta ,  like  D.  capuloides,  but  less  turgid.  Alt.  6.7,  lat.  6.5,  diam. 
4  mm. 

Type  locality. — Bowden,  Jamaica. 

The  incremental  are  stronger  near  the  margin  of  the  shell  than 
elsewhere.  In  the  Dominican  Republic  this  species  apparently  is  con¬ 
fined  to  the  Cercado  formation.  Specimens  from  Bowden  are  slightly 
larger.  Recent  shells  from  Porto  Rico,  St.  Thomas,  and  Jamaica 
apparently  represent  the  same  species,  but  are  not  quite  so  strongly 
inflated. 

Other  localities. — Cercado  formation  (lower  Miocene),  Dominican 
Republic.  Living,  West  Indies. 

Type  material. — Holotype  (right  valve,  Acad.  Nat.  Sci.  Philadel¬ 
phia,  No.  2693). 


132 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Superfamily  ERYCINACEA. 

Family  ERYCINIDAE. 

Genus  ERYCINA  Lamarck. 

Subgenus  ERYCINA  s.  s. 

Lamarck,  1805,  Annales  du  Museum  d’Histoire  Naturelle,  vol.  6,  p.  413. 

Type  (by  subsequent  designation,  Gray  18  47). — Erycina  pellucida 
Lamarck.  Eocene,  Paris  Basin. 

The  following  is  a  description  of  the  subgenus  Erycina  s.  s.: 

Shell  small,  elliptical,  subequilateral  or  inequilateral,  slightly  inflated; 
umbos  low;  sculpture  consisting  of  incrementals;  resilium  seated  on  a  small 
oblique  chondrophore  behind  the  cardinals;  hinge  of  right  valve  consisting 
of  an  oblique  anterior  cardinal  (1)  and  strong  elongate  laterals  forming 
sockets  with  margin  of  valve;  hinge  of  left  valve  consisting  of  a  small 
oblique  anterior  cardinal  (2),  a  minute  middle  cardinal  (4b),  and  weak 
laterals. 

Species  of  Erycina  s.  s.  first  appear  in  Eocene  deposits,  in  which 
they  are  abundant.  They  decline  in  later  Tertiary  time.  Living 
species  are  reported  from  the  West  Indies  and  the  southeast  coast  of 
the  United  States,  but  none  are  known  in  European  waters. 

Key  to  the  Bowden  species  of  Erycina  s.  s. 


Shell  very  inequilateral . E.  ( E .)  olssoni 

Shell  slightly  inequilateral .  E.  (E.)  pura 


Erycina  (Erycina)  olssoni,  new  species. 

(Plate  18,  Figures  4,  5.) 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  elongate,  subquadrate,  very  inequilateral,  anterior  end 
extended;  anterior  dorsal  margin  and  ventral  margin  subparrallel ;  middle 
of  ventral  margin  obscurely  insinuated  by  a  slight  compression  of  shell  near 
margin;  posterior  margin  rounded,  anterior  margin  more  convexly  rounded; 
umbos  low,  placed  near  posterior  end;  sculpture  consisting  of  fine,  incon¬ 
spicuous  incrementals;  right  cardinal  curved  parallel  to  margin;  right 
laterals  strong;  chondrophore  small,  deep. 

Length  4.5  mm.;  height  2.5  mm.;  diameter  (right  valve)  0.8  mm. 

Externally  this  species  resembles  Neaeromya  quadrat  a  Gabb,  de¬ 
scribed  from  the  Dominican  Republic,  but  is  longer  and  more  quad¬ 
rate.  Pilsbry  has  shown  that  N  eaeromy  a  quadrat  a  is  not  an  Erycina, 
as  the  laterals  described  and  figured  by  Gabb  do  not  exist.  An  Erycina, 
very  similar  to  E.  olssoni,  though  smaller,  was  collected  from  the 
Gurabo  formation  of  the  Dominican  Republic. 

Type  material. — Holotype  (right  valve,  1  of  2  specimens  in  Hen¬ 
derson  collection  labeled  Erycina  quadrata  Gabb,  U.  S.  Nat.  Mus.  No. 
135687). 


PELECYPODS. 


133 


Erycina  (Erycina)  pura,  new  species. 

(Plate  18,  Figures  6,  7.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  thin,  substranslucent,  elongate,  moderately  inflated, 
slightly  inequilateral;  anterior  end  extended  and  more  convexly  rounded; 
anterior  dorsal  margin  straight,  gently  sloping,  rounding  into  curve  of 
anterior  end;  posterior  dorsal  margin  shorter,  convex,  curving  more  evenly 
into  the  rounded  posterior  end;  base  straight;  umbo  low,  acute,  placed  be¬ 
hind  the  middle ;  median  ventral  part  of  shell  slightly  constricted ;  sculpture 
consisting  of  fine  concentric  striae;  hinge  of  right  valve  consisting  of  an 
anterior  cardinal  and  strong  laterals;  chondrophore  very  small. 

Length  8  mm.;  height  5  mm.;  diameter  (right  valve)  1.5  mm. 

This  species  is  represented  by  a  right  valve.  It  is  longer  and  less 
inequilateral  than  E.  olssoni.  It  resembles  the  Miocene  and  Pliocene 
species  E.  carolinensis  Dali,  but  is  smaller,  more  elongate,  and  more 
inflated. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352817). 

Family  SPORTELLIDAE? 

Genus  NEAEROMYA  Gabb. 

Gabb,  1872,  Proceedings  Academy  of  Natural  Sciences  of  Philadelphia,  vol.  24, 
p.  274. 

Type  (by  monotypy). — Neaeromya  quadrata  Gabb.  Miocene, 
Dominican  Republic. 

The  following  is  a  description  of  the  genus  Neaeromya: 

Shell  small,  elongate,  subquadrate,  inequilateral,  anterior  end  longer; 
sculpture  consisting  of  concentric  striae,  and  (on  the  type  species)  of 
minute  radial  markings;  hinge  of  right  valve  consisting  of  an  oblique 
anterior  cardinal  (1) ;  left  valve  edentulous,  anterior  margin  of  valve  at 
hinge  functioning  as  a  tooth;  chondrophore  narrow,  directed  obliquely 
backward;  prodissoconch  small,  circular. 

Gabb’s  figure  of  Neaeromya  quadrata  showing  a  left  cardinal  and 
right  and  left  laterals  supported  the  supposition  that  it  represented 
an  Erycina.  Pilsbry  has  shown  that  these  hinge  features  were  imagi¬ 
nary.  Neaeromya  seems  to  be  a  valid  genus.  The  prodissoconch  and 
hinge  of  the  right  valve  resemble  Sportella,  but  there  is  no  trace  of 
an  external  ligament.  The  type  of  the  genus,  the  Bowden  species 
N.  menotreta ,  and  Monacutaf  actinophora  Dali,  from  the  Oak  Grove 
sand  of  Florida,  seem  to  be  the  only  described  species.  Montacuta 
hispaniolae  Maury,  from  the  Cercado  formation  of  the  Dominican 
Republic,  is  a  Neaeromya,  but  seems  to  be  N .  quadrata. 

Neaeromya  menotreta,  new  species. 

(Plate  18,  Figures  8,  9.) 

The  following  is  a  description  of  this  species: 

Shell  small,  slightly  inflated,  elongate  subquadrate,  very  inequilateral; 
anterior  margin  rounded,  posterior  margin  almost  vertically  subtruncate, 


134 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


base  slightly  arcuate,  descending  toward  anterior  end;  posterior  dorsal 
margin  short,  slightly  convex,  sloping  steeply,  rounding  gently  into  posterior 
subtruncation;  umbo  low,  placed  at  about  posterior  third  of  length: 
sculpture  consisting  of  fine  concentric  lamellae;  chondrophore  narrow, 
extending  obliquely  backward;  hinge  of  left  valve  endentulous,  anterior 
margin  of  shell  at  hinge  extended;  right  valve  not  known. 

Length  5.2  mm.;  height  3.5  mm.;  diameter  (left  valve)  1  mm. 

This  species  is  known  only  from  the  holotype,  a  left  valve.  It  is 
similar  to  a  species  described  from  the  Oak  Grove  sand  of  Florida, 
Mont  acuta  f  actinophora  Dali,  but  is  smaller  and  more  inequilateral, 
and  has  stronger  concentric  sculpture  and  no  radial  sculpture.  The 
same  differences  separate  it  from  N.  quadrata  Gabb,  the  type  of  the 
genus,  which  seems  to  be  confined  to  the  Cercado  formation  of  the 
Dominican  Republic. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352818). 

Superfamily  CARDIACEA. 

Family  CARDIIDAE. 

Genus  CARDIUM  Linne. 

Subgenus  CARDIUM  s.  s. 

Linne,  1758,  Systema  Naturae,  ed.  10,  p.  678. 

Type  (by  subsequent  designation,  Gray  1847.) — Cardium  costatum 
Linne.  Recent,  Indo-Pacific. 

The  following  is  a  description  of  the  subgenus  Cardium  s.  s.: 

Shell  large,  quadrate,  strongly  inflated,  equilateral,  gaping  behind;  umbos 
high,  wide;  sculpture  consisting  of  very  wide  ribs  having  high  narrow 
hollow  crests;  hinge  of  right  valve  consisting  of  conical  anterior  (3a)  and 
posterior  (36)  cardinals,  2  anterior  laterals  and  a  posterior  lateral;  hinge 
of  left  valve  consisting  of  2  conical  cardinals  (2  and  46)  placed  almost 
under  each  other,  and  an  anterior  lateral  and  2  posterior  laterals. 

C.  aculeatum  usually  is  given  as  the  type  of  Cardium,  as  Lamarck 
gave  only  this  species  in  the  Prodrome.  According  to  a  rigid  applica¬ 
tion  of  the  rules  this  failed  to  fix  the  type.  Cardiums  of  the  group  of 
C.  costatum  have  been  placed  in  Tropido cardium  Roemer. 

There  are  no  species  of  Cardium  s.  s.  in  the  Bowden  fauna. 

Subgenus  ACANTHOCARDIA  Gray. 

Gray,  1851,  List  of  specimens  of  British  animals  in  collection  of  British 
Museum,  part  7,  p.  23. 

Type  (by  subsequent  designation,  Bucquoy,  Dautzenberg,  and 
Dollfus,  1887). — Cardium  aculeatum  Linne.  Recent,  seas  of  Europe. 

The  following  is  a  description  of  the  subgenus  Acanthocardia: 

Shell  medium-sized,  inequilateral,  rhomboid,  slightly  gaping  at  posterior 
end;  umbos  wide,  high;  sculpture  consisting  of  wide  ribs  having  spines  ris¬ 
ing  from  a  median  groove;  hinge  consisting  of  2  cardinals  in  each  valve 
placed  along  an  oblique  line,  2  right  anterior  laterals,  a  right  posterior 


PELECYPODS. 


135 


lateral,  and  left  anterior  and  posterior  laterals,  indented  on  their  lower 
surface. 

The  difference  in  sculpture  is  the  most  striking  difference  between 
Acanthocardia  and  Cardium  s.  s. 

The  Bowden  species  C.  dissidepictum  does  not  fit  precisely  into  any 
described  group  of  Cardiums.  It  is  not  an  Acanthocardia,  as  its  sculp¬ 
ture  consists  of  open  spines  alternating  in  size  in  successive  rows  in 
the  central  part  of  the  shell.  The  alternating  spines  suggest  the 
Cretaceous  subgenus  Criocardium  Conrad  (type,  Cardium  dumosum 
Conrad),  but  Criocardium  has  solid  spines  rising  from  the  interspaces. 

Similar  Cardiums  are  unknown  in  West  Indian  and  adjacent  Ameri¬ 
can  waters  after  Miocene  time. 

Cardium  (Acanthocardia?)  dissidepictum,  new  species. 

(Plate  18,  Figures  10,  11.) 

The  following  is  a  description  of  this  species: 

Shell  small,  subequilateral,  suborbicular,  lower  part  of  posterior  margin 
obliquely  subtruncate;  umbos  full  and  broad,  but  not  very  high;  sculpture 
consisting  of  43  low  radial  ribs  that  are  flat-topped,  but  slightly  raised  at 
their  margins,  separated  by  narrower,  sharply  defined  channeled  inter¬ 
spaces;  each  rib  bears  a  row  of  laterally  compressed  triangular  large  or 
small  hollow  spines,  their  open  ends  directed  toward  ventral  margin;  in 
middle  part  of  shell  ribs  having  large  spines  alternate  with  ribs  having 
small  spines ;  at  anterior  end  large  spines  predominate  and  at  posterior  end 
small  ones;  internal  surface  bearing  relatively  conspicuous  radial  markings. 

Lenght  23  mm.;  height  23.4  mm.;  diameter  (left  valve)  9.5  mm. 

This  curiously  sculptured  species  is  represented  by  2  complete 
valves  and  several  fragments.  A  restored  broken  valve  has  approxi¬ 
mately  the  following  dimensions:  length  35  mm.;  height  37  mm.; 
diameter  14  mm.  Where  the  spines  have  been  removed  the  ribs  are 
smooth  and  flat  and  their  margins  are  thin  and  slightly  raised;  if 
erosion  proceeds  further,  the  middle  of  the  rib  is  excavated  and  the 
raised  margins  remain  as  narrow  ridges. 

C.  dissidepictum  resembles  C.  acrocome  Dali,  a  species  from  the 
Chipola  formation  of  Florida,  but  is  larger  and  its  long  spines  are  less 
upturned.  It  also  resembles  C.  cinderellae  Maury,  from  the  Gurabo 
formation  of  the  Dominican  Republic,  but  is  smaller  and  has  spines  of 
more  uniform  size. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352819). 

Subgenus  TRACHYCARDIUM  Morch. 

Section  TRACHYCARDIUM  s.  s. 

Morch,  1853,  Catalogus  Conchyliorum  quae  reliquit  D.  Alphonso  cTAguirra  & 
Gadea,  Comes  de  Yoldi,  part  2,  p.  34. 

Type  {by  subsequent  designation,  Dali  1900). — Cardium  isocardia 
Linne.  Recent,  West  Indies. 


136 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  following  is  a  description  of  the  section  Trachycardium  s.  s. : 

Shell  medium-sized,  inequilateral,  high;  sculpture  consisting  of  moderate¬ 
ly  wide  ribs  having  (on  the  type  species)  inverted  U-shaped  lamellae  on 
the  posterior  part  of  their  crest;  hinge  of  right  valve  consisting  of  a  heavy 
posterior  cardinal  (36),  a  scarcely  distinguishable  anterior  cardinal  (3a), 
and  2  anterior  and  posterior  laterals;  hinge  of  left  valve  consisting  of  a 
heavy  anterior  cardinal  (2),  a  scarcely  distinguishable  posterior  cardinal 
(46),  and  an  anterior  and  posterior  lateral  indented  on  their  lower  surface. 

Trachycardium  differs  from  Acanthocardia  principally  in  outline 
and  sculpture.  Species  of  Trachycardium  first  appear  in  Upper  Cre¬ 
taceous  deposits.  The  Tertiary  and  living  species  have  an  extensive 
distribution. 

Key  to  the  Bowden  species  of  Trachycardium . 

Crest  of  ribs  frilled. 

Shell  medium  sized,  height  exceeding  length .  C.  ( T .)  lingualeonis 

Shell  small,  height  and  length  almost  equal .  C.  ( T .)  bowdenense 

Crest  of  ribs  not  frilled. 


Shell  small .  C.  (T.)  inconspicuum 

Shell  large . . .  C.  (T.)  waylandi 


Cardium  (Trachycardium)  lingualeonis  Guppy. 

(Plate  18,  Figures  12,  13.) 

Cardium  lingua-leonis  Guppy,  1866,  Quart.  Jour.  Geol.  Soc.  London,  vol.  22, 
p.  293,  plate  18,  fig.  7.  Guppy,  1874,  Geol.  Mag.,  decade  2,  vol.  1,  p.  422 
(list).  Not  Guppy,  1876,  Quart.  Jour.  Geol.  Soc.  London,  vol.  32,  p.  531 
(  =  C.  dominicanum  Dali,  1900). 

Cardium  ( Trachycardium )  lingualeonis  Guppy,  Dali,  1900,  Trans.  Wagner 
Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  5,  p.  1084. 

The  following  is  the  original  description  of  this  species: 

Shell  elongate,  subquadrate;  valves  deep,  ornamented  with  numerous  (32) 
nodosely  muricate  ribs,  which  are  lower  and  more  distant  toward  the  ante¬ 
rior  and  posterior  margins;  margins  coarsely  crenulate,  the  posterior  one 
strongly  serrate;  hinge  with  3  large  and  stout  teeth. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  moderately  large,  longitudinally  subovate,  strongly  inflated;  umbos 
high,  prominent;  sculpture  consisting  of  31  to  33  strong  radial  ribs  separated 
by  narrow  deeply  channeled  interspaces;  5  anterior  ribs  bear  median,  dis¬ 
connected  globular  nodules  which  on  large  shells  are  absent  from  the 
broader  outer  half  of  the  ribs;  the  next  16  or  17  ribs  ornamented  with  a 
raised  frill  placed  on  the  posterior  side  and  overhanging  the  interspaces, 
the  ornamentation  consisting  of  oblique  medially  swollen  beads  bearing 
attenuated  and  joined  extremities,  producing  a  spiral  effect;  tow'ard  the 
center  of  the  shell  the  frill  becomes  narrower,  beyond  the  center  the  frill 
becomes  wider  and  separated  from  the  smooth  part  of  the  rib  by  a  groove; 
on  the  10  posterior  ribs  the  line  of  beads  gradually  assumes  a  central  posi¬ 
tion  on  the  ribs,  the  beads  themselves  becoming  wider,  transversely  swollen 
or  globular,  and  almost  or  entirely  disconnected;  these  posterior  ribs  are 
lower  and  the  interspaces  wider;  fine  concentric  threads  may  ornament  the 
interspaces  on  any  part  of  the  shell. 

Length  37  mm.;  height  48  mm.;  diameter  (right  valve)  19.5  mm. 


PELECYPODS. 


137 


This  species  is  the  Bowden  representative  of  the  C.  isocardia  Linne 
group.  The  sculpturing  is  very  elaborate  and  on  parts  of  the  shell 
suggests,  as  Dali  has  aptly  remarked,  twisted  ribbons  of  candy.  When 
the  highly  ornamented  frill  is  eroded  the  ribs  are  flat  or  subrounded 
and  smooth,  except  for  a  narrow  median  groove.  Young  shells  are 
less  elongate  and  more  orbicular  than  adults. 

Brown  and  Pilsbry  have  described  a  very  similar  species,  C .  stiri- 
atum,  from  the  Gatun  formation  of  the  Canal  Zone.  It  is  a  little 
smaller  and  has  slightly  heavier  sculpture  of  the  same  type.  C.  lin - 
gualeonis,  C.  stiriatum,  C.  cestum  Dali  (Chipola  formation)  C.  delphi- 
cum  Dali  (Oak  Grove  sand),  C.  emmonsi  Conrad  (Waccamaw  and 
Caloosahatchee  marls),  C.  isocardia  Linne  (Duplin  and  Caloosa- 
hatchee  marls;  Recent,  West  Indies),  and  C.  belcheri  Broderip 
(Recent,  Gulf  of  California)  constitute  a  well-defined  group  and 
differ  principally  in  ornamentation. 

Type  material. — Holotype  (British  Museum,  Natural  History, 
Geological  Department,  No.  64090). 

Cardium  (Trachycardium)  bowdenense  Dali. 

(Plate  18,  Figures  14  to  16.) 

Cardium  ( Trachycardium )  var?  bowdenense  Dali,  1900,  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  5,  pp.  1087-1088. 

Not  Cardium  ( Trachycardium )  bowdenense  Dali,  1915,  Bull.  U.  S.  Nat.  Mus. 
No.  90,  p.  143. 

The  following  is  the  original  description  of  this  species: 

This  species  from  the  Bowden  marl  and  from  the  silex  beds  at  Ballast 
Point,  Tampa  Bay,  Florida,  was  identified  with  the  recent  muricatum  by 
Guppy.  It  has  about  the  same  number  of  ribs  (37  to  41)  and  the  sculpture 
is  much  the  same  in  character,  but  the  similarities  are  all  in  miniature;  the 
shell  is  always  small  (alt.  15.5,  Ion.  15.5,  diam.  9  mm.  for  the  largest  seen), 
less  inflated  proportionally  than  C.  muricatum  of  the  same  size,  with  the 
ribs  more  compressed  and  crowded.  C.  muricatum  has  not  been  found  in 
any  horizon  between  Bowden  and  the  Pleistocene,  which  is  in  itself  a  strong 
reason  for  doubting  whether  the  older  shell  is  identical  with  the  newer.  I 
therefore  propose  for  it  the  name  of  bowdenense,  which,  if  connecting  links 
should  hereafter  be  found,  may  be  regarded  as  of  varietal  value. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  moderately  inflated,  slightly  inequilateral,  suborbicular,  ante¬ 
rior  end  more  convex  than  posterior  and  curving  more  broadly  into  base; 
umbos  low,  moderately  inflated;  sculpture  consisting  of  39  to  42  low, 
subrounded  ribs  separated  by  interspaces  of  the  same  width  or  slightly 
narrower;  interspaces  usually  crossed  by  fine  concentric  threads;  ribs  orna¬ 
mented  with  a  single  row  of  more  or  less  globular  or  transversely  swollen 
beads;  on  the  anterior  8  or  9  ribs  the  beads  are  largest  and  occupy  the 
entire  width  of  the  ribs;  on  the  next  7  ribs  the  beads  are  progressively 
shifted  to  the  anterior  side;  of  the  succeeding  14  ribs  on  the  first  few  the 


138 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


beads  again  occupy  the  entire  width  of  the  rib,  but  on  the  remainder  the 
beads  gradually  are  shifted  to  the  posterior  side  and  the  interspaces  between 
the  ribs  becoming  slightly  deeper;  the  10  posterior  ribs  are  characterized 
by  a  narrow  anterior  keel  and  a  lower  broader  posterior  part  on  which  the 
beads  lie;  interspaces  between  posterior  ribs  relatively  wide  and  shallow. 

Length  19.5  mm.;  height  19.3  mm.;  diameter  (right  valve)  7  mm. 

The  valve  measured  is  much  larger  than  any  other.  The  ribs  on 
the  middle  of  the  shell  are  slightly  narrower  than  those  at  either  end. 
On  most  young  shells  the  low  posterior  part  of  the  10  posterior  ribs  is 
absent,  so  that  the  beads  lie  in  the  interspaces. 

C.  bowdenense  closely  resembles  the  living  West  Indian  C.  muri- 
catum  Linne.  Besides  the  differences  given  in  the  original  description, 
C.  bowdenense  has  more  rounded  beads  and  none  of  the  ribs  bear  two 
rows  of  beads.  These  two  species,  C.  presursor  Dali  (Byram  marl), 
C.  parile  Dali  (Chipola  formation),  C.  virile  Dali  (Chipola  forma¬ 
tion),  C.  malacum  Dali  (Oak  Grove  sand),  and  C.  oedalium  Dali 
(Waccamaw  and  Calooshatchee  marls)  differ  in  size  and  details  of 
sculpture.  The  species  from  the  Tampa  formation  described  as  C. 
bowdenense  is  shorter  and  more  inflated  and  has  slightly  wider  ribs. 

Type  material. — 2  specimens  (probably  cotypes,  but  not  labeled 
types,  U.  S.  Nat.  Mus.  No.  115667). 

Cardium  (Trachycardium)  inconspicuum  Guppy. 

(Plate  19,  Figures  1,  2.) 

Cardium  inconspicuum  Guppy,  1866,  Quart.  Jour.  Geol.  Soc.  London,  vol.  22, 
p.  293,  plate  18,  fig.  12.  Guppy,  1874,  Geol.  Mag.  dec.  2,  vol.  1,  p.  442 
(list).  Not  Guppy,  1876,  Quart.  Jour.  Geol.  Soc.  London,  vol.  32,  p.  531 
(=  C.  dominicense  Gabb,  1873). 

Cardium  ( Trachycardium )  inconspicuum  Guppy,  Dali,  1900,  Trans.  Wagner 
Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  5,  p.  1082. 

The  following  is  the  original  description  of  this  species: 

Shell  elongate,  subtrigonal,  ovate,  ornamented  with  numerous  (38)  imbri¬ 
cate  radiating  ribs  broader  than  their  regularly  squamose  interspaces; 
umbones  scarcely  prominent;  margins  strongly  dentate;  hinge  small,  with 
3  teeth. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  medium-sized,  thin,  subequilateral,  broadly  subovate;  umbos  low; 
sculpture  of  adult  shell  consisting  of  40  or  41  narrow,  low,  subrounded  ribs 
separated  by  narrow  interspaces;  anterior  10  to  13  ribs  ornamented  with 
transverse  or  slightly  oblique  beads;  toward  the  posterior  end  of  the  shell 
the  beads  are  progressively  confined  to  the  lower  end  of  the  ribs;  toward 
the  center  of  the  shell  the  ribs  become  slightly  narrower;  these  ribs,  as  well 
as  the  nonbeaded  parts  of  the  anterior  ribs,  are  crossed  by  arched  concentric 
threads,  the  convex  side  of  the  arch  directed  toward  the  umbo;  in  the 
interspaces  the  concentric  threads  are  inconspicuous;  toward  the  posterior 
end  similarly  sculptured  ribs  become  broader  and  the  interspaces  wider; 


PELECYPODS. 


139 


the  8  posterior  ribs  are  lower  and  smooth,  except  for  a  row  of  distant  fine 
beads  on  their  posterior  edge. 

Length  30  mm.;  height  35  mm.;  diameter  (right  valve)  10.5  mm. 

This  species  resembles  C.  dominicense  Gabb,  a  Miocene  species 
from  the  Dominican  Republic,  but  is  smaller,  and  has  lower  and  nar¬ 
rower  umbos  and  fewer  ribs.  C.  linguatigris  Maury,  from  the  Cercado 
formation  of  the  Dominican  Republic,  closely  resembles  C.  incon- 
spicuum,  but  is  larger  and  apparently  its  relative  height  is  greater. 

A  worn  broken  valve  from  the  Chipola  formation  called  C.  incon- 
spicuum  (U.  S.  Nat.  Mus.  No.  114771)  has  narrower  ribs  and  wider 
interspaces. 

Type  material. — Holotype  (British  Museum,  Natural  History,  Geo¬ 
logical  Department,  No.  64091). 

Cardium  (Trachycardium)  waylandi,  new  species. 

(Plate  19,  Figures  3,  4.) 

The  following  is  a  description  of  this  species: 

Shell  large,  broadly  subovate,  subequilateral,  anterior  margin  curving 
more  convexly  than  posterior;  umbos  full,  moderately  high;  sculpture  con¬ 
sisting  of  35  low,  flat,  broad  radial  ribs,  overhanging  very  narrow,  deeply 
channeled  interspaces ;  lower  part  of  anterior  4  or  5  ribs  obscure,  producing 
an  almost  smooth  slightly  beaded  area;  the  next  23  ribs  have  faint  longi¬ 
tudinal  striae  and  fine  growth-line,  more  prominent  and  oblique  on  the 
anterior  ribs  of  this  series  and  arched  on  the  remaining  ones;  the  edges 
of  the  ribs,  especially  on  the  anterior  side,  are  finely  beaded;  the  last  2  or  3 
interspaces  of  this  series  are  not  channeled;  lower  part  of  the  posterior  8 
ribs  scarcely  separated  by  slightly  depressed  grooves,  which  becomes 
broader  and  deeper  toward  the  umbo,  these  ribs  are  crossed  by  asymmetri¬ 
cally  arched  growth-lines  and  the  last  3  or  4  interspaces  bear,  on  their  upper 
half,  small  globular  beads;  ventral  half  of  interior  surface  bearing  obscure 
grooves  running  up  from  the  fluted  margin. 

Length  50  mm.;  height  63  mm.;  diameter  (right  valve)  20.5. 

This  species  is  represented  by  several  entire  valves  and  fragments 
of  much  larger  ones.  One  of  these  fragments  is  part  of  a  valve  having 
approximately  the  following  dimensions:  length  72  mm.;  height  115 
mm.;  diameter  31  mm.  If  the  surface  is  eroded,  the  ribs  have  the 
appearance  of  bearing  flat  imbricating  arched  scales,  which  on  the 
umbo  are  transformed  into  narrow  transverse  beads.  C.  waylandi 
closely  resembles  C.  decline  Gabb,  a  species  from  Costa  Rica  probably 
of  Miocene  age,  but  is  larger  and  differs  slightly  in  outline.  Both 
species  are  similar  to  the  living  West  Indian  species  known  as  C.  leu- 
costomum  Born,  C.  marmoreum  Lamarck,  and  C.  subelongatum 
Sowerby,  but  have  wider  ribs  and  narrower  interspaces.  Externally, 
C.  waylandi  resembles  a  Pliocene  species  from  Florida,  C.  dalli  Heil- 
prin,  but  has  a  wider  dorsal  margin  and  higher  umbos,  and  lacks  the 
internal  umbonal  ridge  of  C.  dalli. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352822). 


140 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Subgenus  FRA  GUM  Bolten. 

Section  FRA  GUM  s.  s. 

Bolton,  1798,  Museum  Boltenianum,  part  2,  p.  189. 

Type  ( by  subsequent  designation,  Dali  1900), — Cardium  unedo 
Linne.  Recent,  Indo-Pacific. 

The  following  is  a  description  of  the  section  Fragum  s.  s.: 

Shell  medium-sized,  rhomboidal,  strongly  inflated,  posterior  end  truncate, 
posterior  ridge  subangular;  sculpture  consisting  of  many  flat-topped  ribs 
bearing  thin  obscure  beads,  which  usually  are  eroded;  hinge  similar  to 
Trachy  cardium. 

The  truncated  posterior  end  and  posterior  ridge  are  characteristic 
features  of  Fragum  s.  s.  The  earliest  American  species  are  of  Miocene 
age.  No  Tertiary  or  living  species  have  been  described  from  Europe. 
The  living  species  are  confined  to  the  Atlantic  and  Pacific  coasts  of 
American,  and  the  Indo-Pacific  and  West  African  regions. 

Key  to  the  Bowden  species  of  Fragum  s.  s. 

Shell  medium-sized,  posterior  ridge  angular .  C,  ( F .)  medium 

Shell  small,  posterior  ridge  rounded .  C.  ( F .)  elattocostatum 

Cardium  (Fragum)  medium  Linne. 

(Plate  19,  Figures  5,  6.) 

Cardium  medium  Linne,  1758,  Syst.  Nat.,  ed.  10,  p.  678.  Reeve,  1844,  Conch. 
Icon.,  vol.  2,  Cardium,  plate  2,  fig.  30.  Roemer,  1869,  Conch.  Cab.,  Neue 
Ausg.  p.  102,  plate  4,  figs.  5  to  7. 

Cardium  venusium  Dunker,  1861,  Mai.  Blat.,  vol.  6,  p.  37. 

Cardium  ( Fragum )  medium  Linne,  Gabb,  1881,  Jour.  Acad.  Nat.  Sci.  Phila¬ 
delphia,  ser.  2,  vol.  8,  p.  374,  1881.  Dali,  1900,  Trans.  Wagner  Free  Inst. 
Sci.  Philadelphia,  vol.  3,  part  5,  p.  1101-1102.  ?  Glenn,  1904,  Maryland 

Geol.  Survey  Mioc.  vol.,  p.  322,  plate  86,  figs.  6a,  6 b.  Olsson,  1922,  Bull. 
Amer.  Paleontology,  vol.  9,  pp.  389-399,  plate  30,  fig.  6. 

Hemicardium  columba  Heilprin,  1886,  Trans.  Wagner  Free.  Inst.  Sci.  Phila¬ 
delphia,  vol.  1,  p.  93,  plate  11,  fig.  26. 

Cardium  ( Fragrum )  sp.  indet.,  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  5,  p.  1101. 

The  following  is  a  description  of  Bowden  specimens  of  this  species: 

Shell  medium-sized,  roughly  subquadrate;  anterior  margin  rounding 
broadly  into  base;  upper  part  of  posterior  margin  flexed  outward,  lower 
part  subtruncate,  meeting  base  at  an  angle  of  about  90°;  umbos  full,  rela¬ 
tively  high  and  narrow;  posterior  ridge  strong,  subangular;  upper  part  of 
depressed  posterior  area  elevated;  sculpture  consisting  of  36  to  40  low 
subrounded  or  rounded  ribs,  separated  by  narrower  interspaces;  ribs  and 
interspaces  increasing  in  size  from  anterior  end  to  posterior  ridge;  the  8  to 
10  ribs  behind  the  ridge  asymmetrically  rounded,  slightly  overturned  toward 
anterior  end  of  shell ;  unworn  surfaces  of  ribs  showing  arched  narrow  growth 
lines. 

Length  28  mm.;  height  34  mm.;  diameter  (right  valve)  13  mm. 

On  most  shells  the  ribs  are  intact  on  only  a  few  small  patches.  If 
this  surface  is  removed  both  ribs  and  interspaces  bear  fine  concentric 
threads,  which,  as  usual,  are  arched  on  the  ribs. 


PELECYPODS. 


141 


The  largest  Bowden  specimens  are  not  much  more  than  half  as 
large  as  the  largest  living  specimens  of  C.  medium  from  the  West 
Indies,  but  they  seem  to  agree  with  specimens  of  the  same  size. 
Miocene  specimens  from  Costa  Rica  are  larger  than  Bowden  speci¬ 
mens. 

Other  localities. — Gurabo  formation  (middle  Miocene),  Dominican 
Republic.  Gatun  formation  (middle  Miocene),  Costa  Rica.  St. 
Marys  formation  (upper  Miocene),  Maryland  (probably  a  different 
species).  Duplin  marl  (upper  Miocene),  North  Carolina.  Wacca- 
maw  marl  (Pliocene),  North  Carolina.  Caloosahatchee  marl  (Plio¬ 
cene),  Florida.  Living,  Cape  Lookout  to  the  West  Indies  and  Colom¬ 
bia  in  less  than  50  fathoms,  except  in  the  West  Indies,  where  it  occurs 
in  both  shallow  and  deep  water. 

Cardium  (Fragum)  elattocostatum,  new  species. 

(Plate  19,  Figure  7.) 

The  following  is  a  description  of  this  species: 

Shell  small,  subquadrate,  moderately  inflated;  anterior  margin  broadly 
rounded,  posterior  margin  truncate,  base  arcuate,  rounding  into  anterior 
margin  and  meeting  posterior  margin  at  an  angle  of  more  than  90° ;  umbos 
narrow;  posterior  ridge  moderately  strong,  subrounded  or  rounded;  sculp¬ 
ture  consisting  of  18  to  21  subrounded  ribs  on  the  part  of  shell  anterior 
to  ridge,  and  8  to  10  behind  the  ridge;  interspaces  as  wide  as  ribs  in  central 
part  of  shell,  but  narrower  in  posterior  area  and  in  extreme  anterior  part; 
ribs  bearing  at  relatively  distant  intervals  transverse  or  rounded  beads, 
between  which  may  lie  very  fine  concentric  threads;  interspaces  crossed  by 
coarser  narrow  concentric  threads. 

Length  7.9  mm.;  height  8.1  mm.;  diameter  (right  valve)  2.6  mm. 

A  few  smaller  valves  have  a  slightly  insinuated  posterior  margin, 
and  in  this  feature  resemble  C.  medium.  Such  valves  may  readily  be 
distinguished  from  small  specimens  of  C.  medium  of  the  same  size,  as 
they  are  less  inflated,  less  sharply  ridged,  and  have  lower  umbos  and 
fewer  ribs. 

C.  elattocostatum  closely  resembles  C.  burnsii  Dali  from  the  Chipola 
marl  of  Florida,  but  has  higher  and  narrower  umbos,  more  rounded 
posterior  ridge,  fewer  ribs,  deeper  interspaces  and  coarser  concentric 
threads  in  the  interspaces.  The  Bowden  species,  like  C.  burnsii  for 
which  Dali  has  pointed  out  the  relation,  is  intermediate  between 
Fragum  and  Trigoniocardia,  having  the  numerous  similar  ribs  of 
Fragum  and  the  striated  interspaces  of  Trigoniocardia. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352824). 

Section  TRIGONIOCARDIA  Dali. 

Dali,  1900,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  384. 

Type  ( by  original  designation). — Cardium  graniferum  Sowerby. 
Recent,  Pacific  coast  of  Central  America. 


142 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  following  is  a  description  of  the  section  Trigonicardia: 

Shell  small,  strongly  inflated,  rhomboidal,  posterior  end  truncate,  poste¬ 
rior  ridge  subangular;  sculpture  of  part  of  shell  in  front  of  posterior  ridge 
consisting  of  a  few  narrow  ribs  bearing  beads,  which  often  are  eroded; 
interspaces  sculptured  with  looped  concentric  lamellae;  sculpture  of  part 
of  shell  behind  posterior  ridge  consisting  of  lower  and  more  crowded  ribs. 

All  the  described  species  of  Trigoniocardia  are  relatively  small.  The 
interspaces  in  front  of  the  posterior  ridge  are  wider  and  more  elab¬ 
orately  sculptured  than  in  other  sections  of  Fragum.  Living  and 
fossil  species  of  Trigoniocardia  are  confined  to  American  waters — the 
West  Indies,  the  southeast  coast  of  the  United  States,  and  the  Pacific 
coast  of  Central  America.  The  earliest  species  are  of  Eocene  age. 

Key  to  the  Bowden  species  of  Trigoniocardia. 

Posterior  ridge  not  strongly  curved,  13  to  15  ribs  in  front  of  posterior  ridge; 

shell  medium-sized  or  large . . .  C.  (C.)  haitense 

Rib  on  posterior  ridge  not  more  prominent  than  those  in  front  of  ridge. 

C.  (T.)  haitense  haitense 

Rib  on  posterior  ridge  more  prominent  than  those  in  front  of  ridge. 

C.  ( T .)  haitense  cercadicum 

Posterior  ridge  strongly  curved,  10  ribs  in  front  of  posterior  ridge ;  shell  small. 

C.  ( T .)  thaumastum 

Cardium  (Trigoniocardia)  haitense  haitense  Sowerby. 

(Plate  19,  Figures  8,  9.) 

Cardium  haitense  Sowerby,  1849,  Quart.  Jour.  Geol.  Soc.  London,  vol.  6,  p. 
52,  plate  10,  fig.  11.  Guppy,  1866,  Quart.  Jour.  Geol.  Soc.  London,  vol. 
22,  p.  293.  Guppy  (part),  1874,  Geol.  Mag.  decade  2,  vol.  1,  p.  442,  (list.) 
Guppy,  1876,  Quart.  Jour.  Geol.  Soc.  London,  vol.  32,  p.  531. 

Cardium  ( Fragum )  haitense  Sowerby,  Gabb,  1872,  Trans.  Amer.  Philos.  Soc., 
n.  s.,  vol.  15,  p.  251. 

Cardium  ( Trigoniocardia )  haitense  Sowerby,  Maury,  1917,  Bull.  Amer.  Paleon¬ 
tology,  vol.  5,  p.  379,  pi.  62,  figs.  5,  5a.  Maury,  1920,  Scientific  Survey 
Porto  Rico  and  Virgin  Islands,  vol.  3,  part  1,  pp.  35-36,  New  York  Acad. 
Sci.  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  73,  p.  421. 

The  following  is  the  original  description  of  this  subspecies: 

Testa  oblique  subovata  gibbosa,  radiatim  costata,  lateribus  brevibus, 
costis  quatuor  et  viginti,  quadratis,  graniferis,  interstiis  creberrime  regu- 
losos;  angulo  postico  rotundato  ex  umbone  ad  marginem  inferiorem  posti- 
cam  decurrente. 

Type  locality. — Dominican  Republic. 

The  following  is  a  description  of  Bowden  specimens  of  this  sub¬ 
species: 

Shell  relatively  large ;  posterior  margin  almost  vertically  truncate ;  umbos 
full,  high;  part  of  shell  in  front  of  posterior  ridge  sculptured  with  13  to  14 
high,  flat-topped  ribs,  separated  by  squarely  depressed  deep  interspaces  of 
virtually  the  same  width;  area  behind  ridge  bearing  9  lower  ribs,  interspaces 
usually  narrower  than  ribs;  interspaces  sculptured  with  relatively  coarse 
concentric  threads  that  are  arched  (with  the  concave  side  toward  the  umbo) 
in  the  region  immediately  anterior  to  the  ridge  and  also  in  the  posterior 
area  where  they  may  cross  the  ribs;  some  or  all  of  the  ribs  bear  beads  that 


PELECYPODS. 


143 


are  globular  in  the  umbonal  and  the  extreme  anterior  and  posterior  parts 
of  the  shell,  and  transversely  swollen  elsewhere;  the  first  9  or  10  ribs  are 
progressively  wider,  and  the  first  5  or  6  interspaces  wider  than  elsewhere; 
the  remaining  ribs  up  to  the  posterior  ridge  usually  are  squarely  keeled, 
the  concentric  threads  of  the  interspaces  present  on  the  lower  part  of  the 
rib,  but  not  on  the  keel ;  immediately  behind  the  ridge  both  ribs  and  inter¬ 
spaces  are  narrower  than  elsewhere,  but  they  increase  slightly  in  width 
toward  the  posterior  end. 

Length  18  mm.;  height  22  mm.;  diameter  (left  valve)  7  mm. 

This  subspecies  is  the  most  abundant  of  all  the  Bowden  bivalves. 
The  largest  specimens  are  larger  than  specimens  from  the  Gurabo 
formation  of  the  Dominican  Republic,  from  which  the  shells  described 
by  Sowerby  probably  were  collected.  Bowden  specimens  are  con¬ 
siderably  larger  and  have  wider  ribs  than  specimens  from  the  Cercado 
formation. 

Other  localities. — Porto  Rico,  Quebradillas  limestone  ?  (lower  Mio¬ 
cene) ;  Cercado  formation  (lower  Miocene),  Dominican  Republic; 
Gurabo  formation  (middle  Miocene),  Dominican  Republic;  Miocene 
(middle  ?),  Curasao.1 

Type  material. — 10  cotypes  (Geol.  Soc.  London,  No.  12790-12791) 
deposited  in  British  Museum  (Natural  History),  Geological  Depart¬ 
ment. 

Cardium  (Trigoniocardia)  haitense  cercadicum  Maury. 

(Plate  19,  Figures  10,  11.) 

Cardium  ( Trigoniocardia )  haitense  var.  cercadicum  Maury,  1917,  Bull.  Amer. 
Paleontology,  vol.  5,  p.  376,  plate  62,  fig.  6.  Maury,  1920,  Scientific 
Survey  Porto  Rico  and  Virgin  Islands,  vol.  3,  part  1,  p.  36,  New  York 
Acad.  Sci.  Hubbard,  1921,  Scientific  Survey  Porto  Rico'  and  Virgin 
Islands,  vol.  3,  part  2,  p.  117,  plate  19,  fig.  8,  New  York  Acad.  Sci. 

The  following  is  an  abstract  from  the  original  description  of  this 
subspecies : 

This  form  differs  from  the  typical  in  its  sharply  angulated  posterior  slope 
and  produced  posterior  margin.  Ribs  usually  ten  on  the  truncation,  four¬ 
teen  on  the  body,  ornamental  with  nodules  pointing  upward. 

Type  locality. — Bluff  2,  Rio  Mao,  Dominican  Republic. 

The  following  is  a  description  of  Bowden  specimens  of  this  sub¬ 
species  : 

Shell  small,  resembling  in  outline  C.  haitense  haitense,  but  having  a  more 
angular  posterior  ridge;  part  of  shell  in  front  of  ridge  sculptured  with  14 
or  15  narrow,  square  ribs,  separated  by  narrower  squarely,  but  not  very 
deeply,  depressed  interspaces;  rib  on  ridge  wider  and  higher  than  those 
immediately  preceding;  area  behind  ridge  sculptured  with  10  similar,  but 
narrower  ribs,  the  interspaces  much  narrower  than  the  ribs;  ribs  ornamented 
with  beads,  which  are  globular,  except  in  the  median  ventral  part,  where 
they  are  transversely  swollen;  interspaces  sculptured  with  relatively  promi¬ 
nent  concentric  threads. 

Length  11  mm.;  height  13.5  mm.;  diameter  (left  valve)  4.8  mm. 


1  See  footnote  on  page  25. 


144 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


This  subspecies  is  represented  by  a  large  number  of  small  shells  that 
closely  resemble  small  specimens  of  C.  haitense  haitense.  The  empha¬ 
sizing  of  the  angular  posterior  ridge  by  a  rib  that  is  wider,  higher,  and 
more  rounded  than  those  preceding  or  following,  and  the  slightly 
narrower  and  shallower  interspaces  separate  this  subspecies  from 
young  shells  of  C.  haitense  haitense. 

The  interspaces  of  the  Bowden  specimens  are  not  quite  so  deep  as 
on  specimens  from  the  Cercado  formation.  In  the  Dominican  Repub¬ 
lic  this  subspecies  is  confined  to  the  Cercado  formation.  Maury  and 
Hubbard  record  it  from  Miocene  beds  in  Porto  Rico. 

Other  localities. — Cercado  formation  (lower  Miocene),  Dominican 
Republic.  Quebradillas  limestone  and  Ponce  limestone  (lower  Mio¬ 
cene),  Porto  Rico. 

Type  material. — Cornell  University. 

Cardium  (Trigoniocardia)  thaumastum,  new  species. 

(Plate  19,  Figures  12,  13.) 

The  following  is  a  description  of  this  species: 

Shell  small,  oblique,  greatly  inflated;  umbos  high,  strongly  prosogyrate; 
posterior  ridge  angular,  curved;  part  of  shell  in  front  of  ridge  sculptured 
with  10  relatively  wide  ribs,  increasing  in  width  from  anterior  margin  to 
center  of  shell  and  then  slightly  decreasing;  rib  on  the  posterior  ridge 
subrounded,  the  others  flat;  anterior  interspaces  narrower  than  ribs,  toward 
the  ridge  they  become  wider  and  much  deeper;  posterior  area  depressed, 
ornamented  with  7  narrow,  low  flat  ribs,  wider  toward  margin  of  shell; 
some  or  all  ribs  ornamented  with  small  globular  nodules,  becoming  slightly 
transversely  elongate  in  median  ventral  region;  interspaces  sculptured  with 
fine  concentric  threads. 

Length  7.6  mm. ;  height  10  mm. ;  diameter  (right  valve)  4  mm. 

This  species  is  represented  by  the  holotype,  a  right  valve.  It  is 
characterized  by  the  strong  curved  ridge  and  deep  interspaces  between 
the  ribs  immediately  in  front  of  the  ridge.  It  is  similar  to  C.  aminense 
Dali,  from  the  Gurabo  formation  of  the  Dominican  Republic,  but  is 
smaller  and  longer,  and  has  a  more  strongly  curved  posterior  ridge  and 
more  crowded  concentric  threads  in  the  interspaces. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352827). 

Subgenus  LAEVICARDIUM  Swainson. 

Swainson,  1840,  A  Treatise  on  Malacology,  p.  373. 

Type  (by  subsequent  designation,  Bucquoy,  Dautzenberg,  und 
Dollfus,  1887). — Cardium  europaeum  Wood  (=C.  norvegicum  Spen- 
gler).  Recent,  west  coast  of  Europe  and  Mediterranean. 

The  following  is  a  description  of  the  subgenus  Laevicardium : 

Shell  medium-sized,  thin,  obliquely  subovate;  posterior  and  anterior  ends 
smooth,  rest  of  shell  smooth  or  sculptured  with  indistinct  ribs;  laterals 
strongly  bent  upward  and  outward. 


PELECYPODS. 


145 


The  outline,  weak  sculpture  and  bent  laterals  are  characteristic  fea¬ 
tures  of  Laevicardium.  The  Tertiary  and  living  species  have  an  exten¬ 
sive  distribution. 

Cardium  (Laevicardium)  serratum  Linne. 

(Plate  19,  Figures  14  to  16.) 

Cardium  serratum ,  Linne,  1758,  Syst.  Nat.  ed.  10,  p.  680.  Gmelin,  1767,  Syst. 
Nat.,  ed.  12,  p.  1123.  Reeve,  1844,  Conch.  Icon.  vol.  2,  Cardium,  plate  1, 
fig.  1.  d’Orbigny,  1846,  Voy,  Amer.  Merid.,  Mol.,  p.  590.  d’Orbigny,  1853, 
in  de  la  Sagra,  Hist,  phys.,  polit.  et  natur.  de  File  de  Cuba,  Mollusques, 
vol.  2,  p.  304  (French  ed.)  Dali,  1881,  Bull.  Mus.  Compt.  Zool.  Harvard, 
vol.  9,  p.  131.  Dali,  1886,  Bull.  Mus.  Compt.  Zool.  Harvard,  vol.  12,  p. 
270.  Guppy  and  Dali,  1896,  Proc.  U.  S.  Nat.  Mus.,  vol.  19,  p.  327. 

Cardium  citrinum  serratum  Chemnitz,  1782,  Conch.  Cab.,  vol.  6,  p.  194,  plate 
18,  fig.  189. 

Cardium  citrinum  Wood,  1815,  Gen.  Conch.,  p.  223,  plate  54,  fig.  3. 

Cardium  laevigatum  Lamarck  (not  Linne,  or  Born),  1819,  Anim.  sans  Vert., 
vol.  6,  p.  11. 

Cardium  oviputamen  Reeve,  1844,  Conch.  Icon.,  vol.  2,  Cardium,  plate  7, 
fig.  36. 

Liocardium  pictum  Ravenel,  1862,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  for 
1861,  p.  44. 

Cardium  ( Laevicardium )  serratum  Linne,  Gabb,  1881,  Jour.  Acad.  Nat.  Sci. 
Philadelphia,  ser.  2,  vol.  8,  p.  374.  Dali,  1900,  Trans.  Wagner  Free.  Inst. 
Sci.  Philadelphia,  vol.  3,  part  5,  pp.  1110-1111.  Dali,  1901,  Proc.  U.  S. 
Nat.  Mus.,  vol.  23,  p.  387.  Dali  and  Simpson,  1902,  Bull.  U.  S.  Fish 
Comm.,  vol.  20,  part  1,  p.  489.  Brown  and  Pilsbry,  1911,  Proc.  Acad. 
Nat.  Sci.,  Philadelphia,  vol.  63,  p.  367.  Maury,  1917,  Bull.  Amer.  Paleon¬ 
tology,  vol.  5  pp.  376-377,  plate  62,  fig.  8.  Maury,  1920,  Scientific  Survey 
Porto  Rico  and  Virgin  Islands,  vol.  3,  part  1,  pp.  36-37,  New  York  Acad. 
Sci.  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.,  Philadelphia,  vol.  73,  p.  421. 
Olsson,  1922,  Bull.  Amer.  Paleontology,  vol.  9,  p.  400,  plate  30,  figs.  11,  12. 
Not  Laevicardium  serratum  Bose,  1906,  Bol.  Inst.  Geol.  Mexico,  No.  22, 
p.  80,  plate  11,  fig.  5. 

The  following  is  a  description  of  Bowden  specimens  of  this  species: 

Shell  medium-sized,  fragile,  posterior  end  usually  obliquely  extended; 
outline  varying  from  obliquely  subovate-trigonal  to  almost  suborbicular; 
umbos  full,  moderately  high;  posterior  ridge  distinct  on  umbonal  half  of 
shell,  broadly  rounded  on  lower  half;  anterior  and  posterior  ends  of  shell 
having  no  radial  markings,  posterior  smooth  area  wider  than  anterior; 
remainder  of  shell  bearing  numerous  equally  spaced  faint  radial  markings; 
entire  surface  of  shell  having  fine  concentric  markings,  which  are  more 
regular  and  coarser  in  umbonal  region;  inner  margin  of  valve  minutely 
fluted;  ventral  half  of  internal  surface  having  numerous  faint  radii. 

Length  40  mm. ;  height  36  mm. ;  diameter  (left  valve)  13  mm. 

Only  a  few  Bowden  specimens  of  this  species  are  large  and  have 
an  oblique  outline.  Small  valves  have  an  outline  that  ranges  from 
obliquely  elongate  to  almost  subcircular.  The  external  radial  mark¬ 
ings  hardly  affect  the  contour  of  unworn  surfaces  of  the  shell.  The 
surface  is  usually  eroded  and  both  the  radial  and  concentric  markings 
stand  in  slight  relief,  producing  a  cancellate  effect. 

C.  venustum  Gabb,  a  similar  species  from  the  Cercado  formation 
of  the  Dominican  Republic,  has  fuller  and  higher  umbos,  and  heavier 


146 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


cardinals.  C.  serratum  has  been  collected  from  the  Cercado  and 
Gurabo  formations.  C.  dalli  Toula,  from  the  Gatun  formation,  seems 
to  have  more  conspicuous  sculpture.  The  cast  figured  by  Bose  from 
Santa  Maria  Tatetla,  Vera  Cruz,  Mexico,  has  much  wider  umbos  than 
C.  serratum. 

Other  localities. — Quebradillas  limestone  ?  (lower  Miocene),  Porto 
Rico.  Cercado  formation  (lower  Miocene),  Dominican  Republic. 
Gurabo  formation  (middle  Miocene),  Dominican  Republic.  Gatun 
formation  (middle  Miocene),  Panama  Canal  Zone  and  Costa  Rica. 
Choctawhatchee  marl  (upper  Miocene),  Florida.  Caloosahatchee 
marl  (Pliocene),  Florida.  Pleistocene,  southern  Florida.  Living, 
Hatteras  to  the  West  Indies  in  less  than  75  fathoms. 

Genus  PROTO CARDIA  Beyrich. 

Section  PROTOCARDIA  s.  s. 

Beyrich,  1845,  Zeitschrift  fur  Malakozoologie,  Jahrgang  1845,  p.  18. 

Type  (by  subsequent  designation). — Cardium  hillanum  Sowerby. 
Cretaceous,  England.* 1 

The  following  is  a  description  of  the  section  Protocardia  s.  s. : 

Shell  medium-sized,  orbicular-quadrate,  strongly  inflated;  posterior  part 
of  shell  sculptured  with  smooth  radial  ribs,  remainder  of  shell  sculptured 
with  concentric  rugae;  hinge  of  right  valve  consisting  of  a  small  anterior 
cardinal  (3a),  a  heavier  posterior  cardinal  (36),  and  subequal  anterior  and 
posterior  laterals,  the  anterior  one  farther  from  the  cardinals  than  the 
posterior;  hinge  of  left  valve  consisting  of  a  heavy  anterior  cardinal  (2), 
a  smaller  posterior  cardinal  (46),  and  an  anterior  and  posterior  lateral, 
the  anterior  one  larger  and  heavier  than  the  posterior  and  more  upturned; 
margin  of  valve  fluted  at  posterior  end. 

There  seems  to  be  no  Tertiary  or  living  species  of  Protocardia  s.  s. 

Section  NEMOCARDIUM  Meek. 

Meek,  1876,  Report  U.  S.  Geol.  Sur.  of  the  Territories,  vol.  9,  p.  167. 

Type  (by  monotypy) . — Cardium  semiasperum  Deshayes.  Eocene, 
Paris  Basin.2 

The  following  is  a  description  of  the  section  N emocardium: 

Shell  small  or  medium-sized,  orbicular-quadrate,  strongly  inflated,  sub- 
equilateral;  posterior  part  of  shell  sculptured  with  spiny  radial  ribs, 
remainder  of  shell  sculptured  with  smooth  or  beaded  radial  ribs,  or  engraved 
radial  lines;  hinge  resembling  Protocardia  s.  s.,  but  the  right  cardinals  are 
joined;  right  laterals  slightly  upturned,  the  posterior  longer  than  the  ante¬ 
rior;  left  anterior  (2)  cardinal  heavier  and  more  upturned  than  the  posterior 
(46) ;  margin  of  valve  finely  fluted. 

1 1  have  not  had  access  to  specimens  of  the  type  species  showing  the  hinge.  The  description 
of  the  hinge  is  based  on  figures  given  by  Woods  (A  Monograph  of  the  Cretaceous  Lamellibranchia 
of  England,  vol.  2,  part  5,  pp.  197-201,  plate  31,  figs.  6a  to  6c,  plate  32,  figs.  1  to  6,  1908). 

1 1  have  not  seen  the  type  species.  The  description  is  based  on  Cardium  edwardsi  Deshayes, 

Eocene,  Paris  Basin. 


PELECYPODS. 


147 


The  spiny  posterior  ribs,  radial  sculpture  on  the  remainder  of  the 
shell,  and  united  right  cardinals  separate  this  section  from  Protocardia 
s.  s.  Species  are  abundant  in  Eocene  deposits,  but  the  section  declines 
after  Eocene  time.  Some  of  the  Eocene  species  are  large.  In  Europe 
the  section  disappeared  during  Miocene  time,  but  it  is  still  repre¬ 
sented  in  West  Indian  waters  by  P.  peramabilis  Dali  and  P.  tincta 
Dali. 


Protocardia  (Nemocardium)  jamaicensis  Dali. 

(Plate  19,  Figure  17.) 

Protocardia  jamaicensis  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia, 
vol.  3,  part  5,  p.  1114;  1903,  part  6,  plate  48,  fig.  3. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  plump,  subquadrate,  with  rather  high  subcentral  umbones; 
anterior  end  evenly  rounded,  posterior  very  slightly  rounded  truncate; 
surface  with  very  numerous  radiating  threads  crossed  by  concentric  lines 
evenly  disposed,  which  at  the  intersections  reveal  themselves  by  rendering 
the  radii  beaded;  this  sculpture  covers  a  little  less  than  the  anterior  half 
of  the  disk,  behind  which  the  radials  are  narrower  and  not  beaded,  separated 
by  still  narrower  channels;  in  the  channel  separating  the  anterior  from  the 
posterior  type  of  sculpture  rises  a  low  crest  like  a  string  of  small  beads, 
behind  which  in  each  second  or  third  channel  rises  a  row  of  small,  stout, 
very  caducous  spines,  those  on  the  posterior  area  smaller  and  shorter  than 
those  on  the  disk;  internally  the  margin  is  minutely  serrate;  the  hinge 
is  normal.  Lon.  6.2,  alt.  6.0,  diam.  4.5  mm. 

Type  locality. — Bowden,  Jamaica. 

This  species  is  represented  by  the  holotype,  a  left  valve,  and  a 
broken  right  valve.  The  holotype  is  glued  to  cardboard,  so  that  the 
hinge  can  not  be  figured.  It  is  more  orbicular  and  has  lower  umbos 
and  wider  posterior  area  than  P.  islahispaniolae  Maury,  from  the 
Gurabo  formation  of  the  Dominican  Republic,  and  P.  costaricensis 
Olsson,  a  Miocene  species  from  Costa  Rica. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135733). 

Superfamily  ISOCARDIACEA. 

Family  PLIOCARDIIDAE. 

Genus  PLIOCARDIA,  new  genus. 

Type. — Anomalocardia  bowdeniana  Dali.  Miocene,  Jamaica. 

The  following  is  a  description  of  the  genus  Pliocardia: 

Shell  small,  heavy,  ovate,  inequilateral,  posterior  end  rostrate,  base 
slightly  emarginate  in  front  of  rostrum;  lunule  large,  bounded  by  a  deep 
narrow  groove;  sculpture  consisting  of  concentric  rugae;  hinge  consisting 
of  elongate  teeth  lying  under  umbo  and  apparently  representing  anterior 
laterals,  as  in  Isocardia;  on  the  right  valve  there  is  a  broad,  short  anterior 
tooth  (AI),  lying  along  lower  edge  of  hinge  plate,  and  a  long,  curved 
posterior  tooth  (AIII),  its  anterior  end  thin  and  arched,  its  posterior  end 
thick;  left  anterior  tooth  (All)  heavy,  divided  into  a  small  anterior  part 
and  a  heavy  posterior  part;  left  posterior  tooth  (AIV)  thin  and  long;  poste- 


148  MIOCENE  MOLLUSKS  FROM  BOWDEN. 

I 

rior  laterals  absent;  pallial  sinus  very  shallow,  lying  near  posterior  adductor 
scar;  inner  margin  of  valve  bearing  oblique  grooves  except  at  posterior  end. 

This  genus  seems  to  belong  in  the  superfamily  Isocardiacea, 
although  the  anterior  teeth  in  both  valves  are  heavier  and  less 
elongate  than  in  Isocardia.  The  lunule,  rostrate  posterior  end,  and 
shallow  sinus  separate  Pliocardia  from  all  genera  in  the  family  Iso- 
cardiidae.  Therefore,  it  is  put  in  a  new  family  Pliocardiidae.  Plio¬ 
cardia  resembles  the  genus  Vesicomya  Dali,  as  both  genera  have  a 
lunule,  oblique  grooves  on  the  inner  edge  of  the  valves,  and  essentially 
the  same  arrangement  of  teeth.  But  Vesicomya  is  a  thin-shelled  deep¬ 
water  genus;  is  barely  rostrate;  and  has  slender  teeth  of  different 
shape. 

Pliocardia  bowdeniana  (Dali). 

(Plate  20,  Figures  1  to  5.) 

Anomalocardia  bowdeniana  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  6,  pp.  1304-1305,  plate  57,  fig.  7. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  ovate-trigonal,  subrostrate,  with  a  flexuous  base  behind; 
beaks  rather  high,  prosogyrate;  lunule  large,  impressed,  well-defined,  but 
with  no  defined  escutcheon,  posterior  end  pointed,  anterior  rounded,  base 
arcuate,  rather  prominent  mesially;  surface  sculptured  with  concentric 
striae  with  flattish  wider  interspaces;  hinge  normal,  rather  heavy,  inner 
margins  entire;  pallial  sinus  small,  angular.  Length  4.5,  height  3.5, 
diameter  3.0  mm. 

Type  locality. — Bowden,  Jamaica. 

Some  of  the  valves  collected  since  this  species  was  described  are 
considerably  larger  than  the  holotype.  The  largest  has  the  following 
dimensions:  length  10  mm.;  height  7  mm.;  diameter  (right  valve)  2.5 
mm.  The  hinge  and  other  features  are  described  on  page  147.  Appar¬ 
ently  no  similar  species  has  been  described. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135671). 

Superfamily  VENERACEA. 

Family  VENERIDAE. 

Genus  TIVELA  Link. 

Section  TIVELA  s.  s. 

Link,  1807,  Beschreibung  der  Naturalien-Sammlung  der  Universitat  zu  Rostock, 
part  2,  p.  152. 

Type  (by  subsequent  designation,  Dali  1902). — Venus  corbicula 
Gmelin  (=Venus  mactroides  Born).  Recent,  West  Indies. 

The  following  is  a  description  of  the  section  Tivela  s.  s. : 

Shell  medium-sized,  trigonal,  subequilateral,  strongly  inflated;  umbos 
high;  lunule  long,  slightly  depressed;  sculpture  consisting  only  of  mere- 
mentals;  hinge  of  right  valve  consisting  of  2  anterior  lateral  lamellae,  3 


PELECYPODS. 


149 


cardinals  (3a,  1  and  36),  the  upper  surface  of  the  posterior  one  (36)  rugose, 
and  a  narrow  posterior  rugose  area;  hinge  of  left  valve  consisting  of  an 
anterior  lateral,  the  lower  surface  depressed,  4  cardinals  (4a,  2a,  26,  and  46), 
upper  surface  of  third  cardinal  (26)  (from  anterior  end)  rugose,  and  upper 
and  lower  surfaces  of  posteriormost  cardinal  (46)  rugose;  posterior  right 
and  anterior  left  dorsal  margin  grooved;  pallial  sinus  moderately  deep, 
wide,  apex  broadly  -shaped. 

Tivela  jamaicensis  Dali  is  the  only  described  east  American  Tertiary 
species.  An  undescribed  species  from  the  Cercado  formation  of  the 
Dominican  Republic  is  the  earliest  American  species.  The  earliest 
European  species  comes  from  deposits  of  Aquitanian  age.  The  living 
species  are  confined  to  tropical  West  Indian  and  west  African  waters, 
and  the  Pacific  coast  of  Central  America. 

Tivela  (Tivela)  jamaicensis  Dali. 

(Plate  20,  Figures  6,  7.) 

Tivela  jamaicensis  Dali,  1903,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia, 
vol.  3,  part  6,  pp.  1244-1245,  plate  57,  fig.  9. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  thin,  plump,  smooth,  or  faintly  concentrically  striated;  beaks 
nearly  central,  low,  pointed,  turgid;  lunule  large,  lanceolate,  smooth,  defined 
by  an  impressed  line;  nymphs  short  and  elevated,  dorsal  slopes  nearly 
straight,  ends  bluntly  rounded,  base  slightly  arcuate;  hinge  delicate,  with 
3  small  cardinals  and  a  rather  long,  slender,  anterior  left  lateral;  margins 
thin,  smooth;  pallial  sinus  small,  rounded.  Length  6.0,  height  5.5,  diameter 
4.0  mm. 

Type  locality. — Bowden,  Jamaica. 

The  holotype,  a  left  valve,  is  the  only  specimen  of  this  species.  It 
resembles  T.  abaconis  Dali,  a  living  species  from  the  Bahamas,  in 
having  a  long,  slender  left  anterior  lateral,  which  is  distant  from  the 
cardinals.  It  is  much  smaller  than  an  undescribed  species  from  the 
Cercado  formation  of  the  Dominican  Republic. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135675). 

Genus  GAFRARIUM  Bolton. 

Subgenus  GAFRARIUM  s.  s. 

Section  GAFRARIUM  s.  s. 

Bolten,  1798,  Museum  Boltenianum,  part  2,  p.  176. 

Type  (by  subsequent  designation,  Dali  1902). — Venus  pectinata 
Linne.  Recent,  Indo-Pacific. 

The  following  is  a  description  of  the  section  Gajrarium  s.  s.: 

Shell  medium-sized,  ovate,  moderately  inflated,  umbos  low;  lunule  nar¬ 
row,  limited  by  a  narrow  groove;  sculpture  consisting  of  beaded  radial 
threads,  divaricating  at  posterior  end;  hinge  of  right  valve  consisting  of 
2  anterior  lateral  lamellae  and  3  cardinals  (3a,  1  and  36) ;  hinge  of  left 
valve  consisting  of  an  anterior  lateral,  its  lower  surface  depressed,  and  3 
cardinals  (2a,  26,  46),  the  middle  one  (26)  heavy  and  grooved  on  the 


150 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


anterior  face;  pallial  sinus  barely  indenting  pallial  line;  inner  ventral 
margin  fluted. 

There  are  no  American  species  of  Gajrarium  s.  s. 

Section  GOULDIA  C.  B.  Adams. 

C.  B.  Adams,  1847,  Catalogue  of  Genera  and  Species  of  Recent  Shells  in 
Collection  of  C.  B.  Adams,  p.  29. 

Type  (by  subsequent  designation,  Dali  1902). — Thetis  cerina  C.  B. 
Adams.  Recent,  West  Indies. 

The  following  is  a  description  of  the  section  Gouldia: 

Shell  small,  trigonal-ovate;  lunule  long,  narrow,  slightly  depressed; 
sculpture  consisting  of  concentric  rugae  and  less  distinct  radial  threads; 
hinge  resembling  Gajrarium  s.  s.,  but  the  teeth  are  more  slender  and  the 
middle  left  cardinal  (26)  is  not  grooved;  inner  ventral  margin  not  fluted; 
inner  dorsal  margins  grooved. 

The  differences  in  hinge  and  sculpture  separate  Gouldia  from  Gafra- 
rium  s.  s.  According  to  Cossmann,  Gouldia  probably  is  represented 
in  the  Eocene  deposits  of  the  Paris  Basin.  No  European  Oligocene 
species  are  known,  but  species  appear  in  the  Aquitanian  and  the  group 
continues  to  the  present  time  in  European  waters.  The  earliest  Amer¬ 
ican  species  are  of  lower  Miocene  age  and  species  are  now  living  in 
American  waters.  No  living  species  are  known  on  the  Pacific  coast  of 
America. 

Gafrarium  (Gouldia)  insular e  (Dali  and  Simpson). 

(Plate  20,  Figures  8  to  10.) 

Circe  ( Gouldia )  insulare  Dali  and  Simpson,  1901,  Bull.  U.  S.  Fish  Comm.,  vol. 
20,  part  1,  p.  487,  plate  55,  fig.  2. 

Gajrarium,  ( Gouldia )  insulare  (Dali  and  Simpson),  Dali,  1903,  Trans.  Wagner 
Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  6,  p.  1248. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  yellowish  white,  quite  inequilateral,  moderately  convex,  with 
a  prominent,  rather  anterior  beak;  sculpture  of  small,  close-set,  subequal, 
concentric  undulations,  with  narrower  interspaces  and  less  pronounced  on 
the  umbones,  crossed  by  fine  radial  striae,  which  are  stronger  towards  the 
ends  of  the  valves,  where  the  interspaces  sometimes  become  threadlike; 
lunule  small,  sharply  defined,  rather  long  and  narrow;  escutcheon  absent; 
interior  white,  the  margins  in  many  specimens  with  a  fine  sulcus  parallel 
to  it  around  the  shell ;  hinge  normal ;  pallial  line  entire  but  slightly  truncate 
behind.  Length  5.5;  height  5;  diameter  3  mm. 

Type  locality. — Mayaguez  Harbor,  Porto  Rico. 

This  small  species  is  very  abundant.  A  typical  adult  shell  has  the 
following  dimensions:  length  6.2  mm.;  height  5.5  mm.;  diameter  (left 
valves)  3.5  mm.  Young  shells  are  more  orbicular  than  adults,  and 
usually  have  a  poorly  defined  lunule.  Some  shells,  especially  young 
ones,  are  more  inflated  than  others,  and  have  higher  umbos  and  more 


PELECYPODS. 


151 


slender  teeth.  The  sculpture  is  variable,  but  the  radial  threads  are 
strongest  at  the  ends  of  the  shell. 

The  Bowden  shells  seem  to  be  the  same  as  living  Porto  Rican  shells. 
Gafrarium  limonensis  Olsson,1  described  from  Miocene  beds  in  Costa 
Rica,  is  very  similar. 

Other  localities. — Living,  San  Juan  and  Mayaguez  Harbors,  Porto 
Rico,  in  5  to  30  fathoms. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  160061). 

Genus  CALLOCARDIA  A.  Adams. 

Subgenus  CALLOCARDIA  s.  s. 

A.  Adams,  1863,  Annals  and  Magazine  of  Natural  History,  ser.  3,  vol.  13, 
p.  307. 

Type  {by  monotypy). — Callocardia  guttata  A.  Adams.  Recent, 
Seas  of  China  and  Japan.2 

The  following  is  a  description  of  the  subgenus  Callocardia  s.  s. : 

Shell  small,  thin,  ovate,  strongly  inflated;  lunule  large,  limited  by  a 
slightly  depressed  groove;  sculpture  consisting  of  concentric  rugae;  hinge 
of  right  valve  consisting  of  2  anterior  lateral  lamellae  and  3  cardinals  (3a, 
1  and  36) ;  hinge  of  left  valve  consisting  of  an  anterior  lateral  and  3  car¬ 
dinals  (2a,  26,  and  46) ;  anterior  and  posterior  right  cardinals  (3a  and  36) 
joined  and  arching  over  middle  cardinal  (1) ;  anterior  and  middle  left 
cardinals  (2a  and  26)  similarly  joined;  posterior  right  and  anterior  left 
dorsal  margins  grooved  to  receive  edge  of  opposite  valve;  pallial  sinus 
shallow. 

The  Bowden  species  placed  in  this  genus  are  very  small,  but  the 
large  number  of  shells  representing  them  indicate  that  the  largest  are 
full  grown.  The  left  anterior  lateral  is  more  elongate  than  in  C.  vesica, 
and  3a  and  36  are  not  so  clearly  joined. 

Species  of  Callocardia  first  appeared  in  the  Eocene  seas.  The  living 
species  are  widely  distributed  in  warm-temperate  and  tropical  waters. 

Key  to  the  Bowden  species  oj  Callocardia  s.  s. 

Umbos  low,  concentric  rugae  usually  irregularly  spaced .  C.  ( C .)  ammondea 

Umbos  relatively  high  and  full,  concentric  rugae  uniformly  spaced...  C.  ( C .)  elethusa 

Callocardia  (Callocardia)  ammondea,  new  species. 

(Plate  20,  Figures  11,  12.) 

Callocardia  sp.  indet.,  Dali.  1903  (part),  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  6,  p.  1261. 

The  following  is  a  description  of  this  species: 

Shell  small,  strongly  inflated,  slightly  inequilateral,  rounded-trigonal  or 
broadly  ovate;  lunule  large,  limited  by  a  shallow  groove;  sculpture  con¬ 
sisting  of  irregularly  spaced  concentric  rugae;  anterior  left  cardinal  long 
and  narrow;  right  anterior  (3a)  and  posterior  (36)  cardinals  obscurely 
joined;  posterior  right  and  anterior  left  dorsal  margins  grooved;  anterior 


1  Comparison  based  on  figures. 

J I  have  not  seen  the  type  species.  The  description  is  based  on  Callocardia  vesica  (Dali),  a 
living  species  from  the  Gulf  of  Mexico  and  the  West  Indies. 


152 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


dorsal  margin  of  some  right  valves,  and  ventral  margin  of  some  left  and 
right  valves,  similarly  grooved. 

Length  7.5  mm.;  height  7  mm.;  diameter  (left  valve)  2.2  mm. 

Some  shells  are  more  ovate  and  have  stronger  and  more  regular 
sculpture  than  the  holotype.  Alternating  opaque  and  partly  trans¬ 
lucent  concentric  bands  are  visible  on  some  specimens.  All  the  Amer¬ 
ican  Miocene  Callocardias  heretofore  described  belong  to  the  subgenus 
Agriopoma,  which  is  characterized  by  large  heavy  valves,  obscure 
right  anterior  lateral  lamellae,  and  a  deep  angular  pallia!  sinus. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352830). 

Callocardia  (Callocardia)  elethusa,  new  species. 

(Plate  20,  Figures  13,  14.) 

The  following  is  a  description  of  this  species: 

Shell  small,  strongly  inflated,  ovate;  umbos  high  and  full;  lunule  wide 
and  long;  sculpture  consisting  of  closely  and  evenly  spaced  concentric 
rugae;  hinge  and  inner  edge  of  valve  as  in  Callocardia  ammondea. 

Length  8.5  mm.;  height  7.5  mm.;  diameter  (left  valve)  2.5  mm. 

The  holotype  is  considerably  larger  than  any  other  valve.  This 
species  is  more  inflated  than  C.  ammondea ,  and  has  higher,  fuller 
umbos,  wider  lunule,  and  more  uniform  sculpture. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352831). 

Genus  PITAR  Romer. 

Subgenus  PITAR  s.  s. 

Section  PITAR  s.  s. 

Romer,  1857,  Kritische  Untersuchung  der  Arten  des  Molluskengeschlechts 
Venus  bei  Linne  und  Gmelin,  p.  15. 

Type  {by  monotypy) . — Venus  tumens  Gmelin.  Recent,  west  coast 
of  Africa. 

The  following  is  a  description  of  the  section  Pitar  s.  s.: 

Shell  medium-sized,  trigonal-ovate,  strongly  inflated;  lunule  wide,  limited 
by  a  slightly  depressed  groove;  escutcheon  indistinct;  sculpture  consisting 
of  incrementals ;  hinge  of  right  valve  consisting  of  2  indistinct  anterior 
lateral  lamellae  flanking  a  deep  socket,  and  3  cardinals,  the  anterior  (3a) 
and  middle  (1)  ones  almost  perpendicular  to  hinge-margin,  the  middle  one 
heavy,  the  posterior  one  (36)  bifid;  hinge  of  left  valve  consisting  of  a  heavy 
anterior  lateral  and  3  cardinals,  the  anterior  one  (2a)  resembling  the  right 
anterior  cardinal  (3a),  the  middle  one  (26)  very  heavy  and  obscurely  bifid, 
the  posterior  one  (46)  slender  and  partly  joined  to  the  nymph;  pallial  sinus 
deep,  its  apex  acutely  angular. 

There  are  no  Bowden  species  of  Pitar  s.  s. 

Section  HYPANTHOSOMA  Dali. 

Dali,  1902,  Proceedings  U.  S.  Nat.  Mus.,  vol.  26,  p.  354. 

Type  {by  original  designation). — Cytherea  carbasea  Guppy.  Mio¬ 
cene,  Jamaica. 


PELECYPODS. 


153 


The  following  is  a  description  of  the  section  Hyphantosma: 

Shell  resembling  Pitar  s.  s.,  but  the  right  anterior  lateral  lamellae  are 
more  prominent;  the  right  posterior  cardinal  (36)  is  very  deeply  bifid, 
separating  it  into  two  distinct  parts ;  the  left  anterior  lateral  is  not  parallel 
to  the  hinge  margin;  the  left  middle  cardinal  (26)  is  not  grooved;  arid  the 
left  posterior  cardinal  (46)  is  more  distinctly  separated  from  the  nymph; 
sculpture  consisting  of  zigzag  grooves. 

Hyphantosoma  is  a  strictly  American  group,  as  fossil  and  living 
species  are  confined  to  the  West  Indies  and  adjoining  waters.  The 
earliest  species  is  from  beds  of  middle  Oligocene  age  in  Porto  Rico.  In 
other  parts  of  the  West  Indies  the  earliest  species  is  of  Miocene  age. 

Pitar  (Hyphantosoma)  carbaseus  (Guppy) 

(Plate  20,  Figures  15  to  19.) 

Cytherea  (Circe)  carbasea  Guppy,  1866,  Quart.  Jour.  Geol.  Soc.  London,  vol. 
22,  p.  292,  plate  18,  fig.  13. 

Callista  carbasea  (Guppy),  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol. 

15,  p.  250. 

Cytherea  cabasea  Guppy,  Guppy,  1874,  Geol.  Mag.  decade  2,  vol.  1,  p.  442 
(list).  Guppy,  1876,  Quart.  Jour.  Geol.  Soc.  London,  vol.  32,  p.  531. 

Pitaria  ( Hyphantosoma )  carbasea  (Guppy),  Dali,  1903,  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  6,  p.  1266.  ?  Hubbard,  1921,  Scientific 

Survey  Porto  Rico  and  Virgin  Islands,  vol.  3,  part  2,  pp.  121-122,  plate 

16,  fig.  2,  New  York  Acad.  Sci.  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci. 
Philadelphia,  vol.  73,  p.  422. 

Pitaria  ( Hyphantosoma )  n.  sp.,  Toula,  1908,  Jahrb.  K.  K.  geol.  Reichsanstalt, 
vol.  58,  pp.  726-727,  plate  28,  fig.  16. 

Pitar  centangulata  Brown  and  Pilsbry,  1911,  Jour.  Acad.  Nat.  Sci.  Philadelphia, 
vol.  63,  pp.  369-370. 

Pitaria  carbasea  (Guppy),  Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5.  p.  380. 

The  following  is  the  original  description  of  this  species: 

Shell  rounded,  rather  inequilateral,  tumid,  sulcated  by  lines  of  growth 
decussating  with  numerous  radiating  striae,  which  divaricate  on  the  anterior 
part  of  the  disk,  and  become  subrugose  towards  the  posterior  margin; 
lunule  large,  scarcely  distinct;  posterior  margin  rounded;  anterior  margin 
somewhat  produced. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  medium-sized,  thin,  strongly  inflated,  ovate,  moderately  inequi¬ 
lateral;  umbos  full,  strongly  prosogyrate;  lunule  large,  groove  at  its  outer 
edge  shallow  except  near  lower  margin;  sculpture  consisting  of  radial 
grooves,  curved  upward  at  ends  of  shell,  zigzag  in  central  part  of  shell; 
concentric  wrinkles  prominent  at  ends  of  shell;  radial  sculpture  absent  on 
lunule  and  umbo. 

Length  39.5  mm.;  height  32.5  mm.;  diameter  (right  valve)  12.5  mm. 

Specimens  of  this  species  in  the  Gabb  collection  from  the  Dominican 
Republic  are  smaller  and  have  weaker  concentric  sculpture.  A  similar 
specimen  was  collected  by  the  U.  S.  Geological  Survey  expedition 
from  beds  carrying  a  Cercado  fauna  modified  by  the  first  appearance 


154 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


of  Gurabo  species.  P.  centangulata,  from  the  Gatun  formation,  can 
hardly  be  separated.  The  holotype  is  worn,  but  has  the  shape  and 
sculpture  of  P.  carbaseus,  although  it  is  slightly  less  elongate  and 
slightly  more  inflated. 

Dali  has  commented  on  the  progressive  weakening  of  the  character¬ 
istic  sculpture  in  progressively  younger  species.  P.  floridanus  Dali 
(Chipola  formation),  P.  opisthogrammatus  Dali  (Caloosahatchee 
marl),  and  P.  simpsoni  Dali  (living)  are  a  series  showing  this  feature. 
The  zigzag  sculpture  is  not  noticeable  on  unworn  shells  of  the  living 
species.  These  species  differ  from  P.  carbaseus  in  outline  and  in 
having  weaker  sculpture. 

Hubbard  recorded  as  P.  carbaseus  poorly  preserved  casts  from  mid¬ 
dle  Oligocene  beds  in  Porto  Rico. 

Other  localities. — ?  San  Sebastian  shale,  Lares  limestone,  and  Cibao 
limestone  (middle  Oligocene),  Porto  Rico.  Cercado  formation  (lower 
Miocene),  Dominican  Republic.  Gatun  formation  (middle  Miocene), 
Panama  Canal  Zone. 

Type  material. — Holotype,  British  Museum  (Natural  History), 
Geological  Department,  No.  64086. 

Subgenus  HYSTEROCONCHA  Fischer. 

Section  HYSTEROCONCHA  s.  s. 

Fischer,  1887,  Manuel  de  Conchyliologie,  p.  1079. 

Type  (by  monotypy). — Venus  dione  Linne.  Recent,  West  Indies. 

The  following  is  a  description  of  the  section  Hysteroconcha  s.  s. : 

Shell  medium-sized,  ovate;  lunule  small,  depressed;  escutcheon  long, 
narrow,  limited  by  a  wide  depression;  sculpture  (of  the  type  species)  con¬ 
sisting  of  frilled  concentric  lamellae;  on  the  posterior  slope  the  lamellae 
are  not  frilled;  at  the  edge  of  the  posterior  slope  is  a  radial  row  of  spines; 
a  shorter  row  of  smaller  spines  lies  farther  back  on  the  posterior  slope; 
hinge  of  right  valve  consisting  of  2  low  anterior  lateral  lamellae,  and  3 
cardinals,  the  anterior  (3a)  and  middle  (1)  ones  close  together,  the  posterior 
one  (36)  deeply  bifid  and  joined  to  the  anterior  one  (3a)  by  a  thin  plate; 
hinge  of  left  valve  consisting  of  a  prominent  anterior  lateral,  and  3  cardi¬ 
nals,  the  anterior  one  (2a)  slender,  the  middle  one  (26)  heavy,  the  posterior 
one  (46)  slender  and  obscurely  bifid;  inner  edge  of  nymph  having  fine 
transverse  granules;  pallial  sinus  wide,  moderately  deep,  apex  broadly 
U-shaped. 

The  pallial  sinus  is  much  wider  than  in  Pitar  s.  s.,  and  the  pallial 
line  is  closer  to  the  margin  of  the  shell. 

The  Bowden  species,  Cytherea  planivieta  Guppy,  has  been  placed 
in  the  section  Lamelliconcha  Dali.  The  type  of  Lameiliconcha,  Cy¬ 
therea  concinna  Sowerby,  a  species  living  on  the  Pacific  coast  of 
Central  America,  has  a  slightly  emarginate  base,  very  deep,  relatively 
narrow  pallial  sinus  having  a  narrow  asymmetric  U -shaped  apex; 
and  the  nymph  has  no  granules.  Despite  the  absence  of  an  escutcheon 


PELECYPODS. 


155 


and  the  striking  difference  in  sculpture  the  Bowden  species  seems  to 
be  more  similar  to  Venus  dione.  The  right  anterior  cardinal  (3a)  is 
undercut  in  both  Cytherea  concinna  and  in  Venus  dione,  but  not  in 
Cytherea  planivieta. 

Externally  the  Bowden  species  closely  resembles  Cytherea  eryci- 
noides  Lamarck,  a  Miocene  species  from  Aquitaine.  The  right  ante¬ 
rior  (3a)  and  posterior  (36)  cardinals  of  Cytherea  erycinoides  are 
not  joined,  its  nymph  has  no  granules,  and  its  pallial  sinus  has  a  broad 
asymmetric  V-shaped  apex,  the  angle  lying  at  the  lower  limb.  This 
species  is  placed  in  the  genus  Callista  Poli  by  French  paleontologists, 
a  name  that  Dali  discards  for  Macrocallista  Meek,  on  the  ground  that 
Poli’s  names  are  polynomial. 

The  living  species  of  Hysteroconcha  are  characteristic  of  tropical 
American  seas. 

Pitar  (Hysteroconcha)  planivietus  (Guppy). 

(Plate  21,  Figures  1  to  4.) 

Cytherea  ( Callista )  'planivieta  Guppy,  1866,  Quart.  Jour.  Geol.  Soc.  London, 
vol.  22,  p.  292,  plate  18,  fig.  3. 

Callista  planivieta  (Guppy),  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol. 
15,  p.  250. 

Cytherea  planivieta  Guppy,  Guppy,  1874,  Geol.  Mag.,  decade  2,  vol.  1,  p. 
442  (list).  Guppy,  1876,  Quart.  Jour.  Geol.  Soc.  London,  vol.  32,  p.  531. 
Not  Grzybowski,  1899,  Neues  Jahrbuch,  Beilage  Band,  vol.  12,  p.  639, 
plate  19,  fig.  3. 

Pitaria  ( Lamelliconcha )  planivieta  (Guppy),  Dali.  1903,  Trans.  Wagner  Free 
Inst.  Sci.,  Philadelphia,  vol.  3,  part  6,  p.  1268.  Not  Spieker,  1922,  Johns 
Hopkins  Univ.  Studies  in  Geology,  No.  3,  pp.  147-149,  plate  10,  fig.  6. 

Pitana  planivieta  (Guppy),  Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5, 
p.  381,  plate  63,  fig.  3. 

Macrocallista  ( Chionella )  planivieta  (Guppy),  Pilsbry,  1922,  Proc.  Acad.  Nat. 
Sci.  Philadelphia,  vol.  73,  p.  422. 

The  following  is  the  original  description  of  this  species: 

Shell  inequilateral,  transverse,  oval,  compressed;  valves  polished,  orna¬ 
mented  with  numerous  flat,  slightly  irregular,  concentric  ribs,  which  are 
much  closer  than  their  interstices;  umbones  prominent,  approximated; 
lunule  scarcely  impressed. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  large,  polished,  moderately  inflated,  very  inequilateral,  elongate- 
ovate;  lunule  small,  depressed;  sculpture  consisting  of  coarse  concentric 
rugae,  on  which  microscopic  striae  are  engraved;  anterior  lateral  close  to 
cardinals;  right  anterior  cardinal  (3a)  not  undercut;  inner  edge  of  nymph 
bearing  transverse  granules;  pallial  sinus  wide,  apex  U-shaped. 

Length  51  mm.;  height  39.5  mm.;  diameter  (right  valve)  10.5  mm. 

This  species  is  one  of  the  most  abundant  veneroids.  Its  shape  and 
regular  sculpture  are  characteristic  features.  The  granules  on  the 
nymph  are  most  conspicuous  on  young  shells.  Specimens  from  the 
Cercado  and  Gurabo  formations  of  the  Dominican  Republic  closely 


156 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


resemble  Bowden  shells,  but  are  smaller  and  have  a  slightly  wider 
posterior  slope.  Poorly  preserved  specimens  of  a  similar  Pitar  from 
White  Beach,  Florida,  are  virtually  indeterminable.  The  Pitar  from 
the  Zorritos  formation  of  Peru,  described  by  Grzybowski  and  Spieker, 
apparently  represents  a  different  species,  as  it  is  less  elongate,  and  has 
higher  umbos,  heavier  hinge,  and  more  distant  rugae. 

Other  localities. — Cercado  formation  (lower  Miocene)  and  Gurabo 
formation  (middle  Miocene),  Dominican  Republic. 

Type  material. — Holotype,  British  Museum  (Natural  History), 
Geological  Department,  No.  64085. 

Genus  ANTIGONA  Schumacher. 

Subgenus  ANTIGONA  s.  s. 

Section  ANTIGONA  s.  s. 

Schumacher,  1817,  Essai  (Tun  Nouveau  Systeme  des  Habitations  des  Vers 
Testaces,  p.  154. 

Type  (by  monotypy) . — Antigona  lamellaris  Schumacher.  Recent, 
Indo-Pacific. 

The  following  is  a  description  of  the  section  Antigona  s.  s.: 

Shell  medium-sized,  elongate  ovate;  lunule  wide,  limited  by  a  deep 
groove;  escutcheon  long,  excavated;  sculpture  consisting  of  distant  con¬ 
centric  frills  and  wide  radial  threads  frilling  the  lamellae;  hinge  of  right 
valve  consisting  of  2  small  lateral  lamellae,  and  3  cardinals,  the  anterior 
one  (3a)  thin  and  parallel  to  the  hinge-margin,  the  posterior  one  (35)  wide 
and  deeply  bifid;  hinge  of  left  valve  consisting  of  a  small  anterior  lateral, 
and  3  cardinals,  the  anterior  one  (2a)  obscurely  bifid,  the  middle  one  (25) 
deeply  bifid;  palial  sinus  shallow,  V  -shaped;  ventral  margin  fluted  along 
edge  of  lunule. 

There  are  no  Bowden  species  of  Antigona  s.  s. 

Subgenus  VENTRICOLA  Romer. 

Section  VENTRICOLA  s.  s. 

Romer,  1867,  Malakozoologische  Blater,  Band  14,  p.  115. 

Type  (by  subsequent  designation,  Dali,  1902). — Venus  rugosa 
Gmelin  (=Venus  rigida  Dillwyn).  Recent,  West  Indies. 

The  following  is  a  description  of  the  section  Ventricola  s.  s.: 

Shell  reaching  a  moderately  large  size,  orbicular-ovate,  strongly  inflated; 
lunule  wide,  deeply  depressed;  escutcheon  flattened  on  left  valve,  absent 
on  right;  sculpture  consisting  of  frilled  concentric  lamellae;  hinge  of  right 
valve  consisting  of  2  low  anterior  lateral  lamellae,  and  3  heavy  cardinals, 
the  middle  (1)  and  posterior  (35)  ones  bifid;  hinge  of  left  valve  consisting 
of  a  small  anterior  lateral  at  base  of  hinge  plate,  and  3  cardinals,  the 
anterior  (2a)  and  middle  (25)  ones  heavy,  the  middle  one  bifid;  pallial 
sinus  shallow,  its  apex  v-shaped;  ventral  margin  of  valve  fluted,  the  fluting 
extending  without  interruption  around  edge  of  lunule. 

The  principal  differences  between  Ventricola  and  Antigona  s.  s.,  are 
in  details  of  the  hinge.  Clausina  Brown  (type,  Venus  verrucosa 


PELECYPODS. 


157 


Linne),  considered  synonymous  with  Ventricola  by  Cossmann,  has  no 
right  anterior  lateral  lamellae,  and  only  a  rudimentary  left  anterior 
lateral.  There  seems  to  be  no  essential  difference  between  Ventricola 
and  V entricoloidea  Sacco  (type,  Cytherea  multilamella  Lamarck), 
which  is  represented  by  Oligocene,  Miocene,  Pliocene,  and  living 
species  in  southern  Europe.  The  earliest  American  species  is  from 
the  Red  Bluff  clay  (lower  Oligocene).  The  living  species  are  most 
abundant  in  tropical  waters,  particularly  in  the  West  Indies,  the  west 
coast  of  Central  America,  and  the  Indo-Pacific  region. 

Antigona  (Ventricola)  blandiana  (Guppy). 

(Plate  21,  Figures  5  to  9.) 

Venus  blandiana  Guppy,  1873,  Proc.  Sci.  Assoc.  Trinidad,  vol.  3,  pp.  85-86, 
plate  2,  fig.  8.  Guppy,  1874,  Geol.  Mag.  decade  2,  vol.  1,  p.  436,  plate  17, 
fig.  8,  p.  442  (list).  Guppy,  1876,  Quart.  Jour.  Geol.  Soc.  London,  vol.  32, 
p.  530. 

Cytherea  ( Ventricola )  blandiana  (Guppy),  Dali,  1903,  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  6,  p.  1277.  Pilsbry,  1922,  Proc.  Acad. 
Nat.  Sci.  Philadelphia,  vol.  73,  p.  424. 

Antigona  ( Ventricola )  blandiana  (Guppy),  Maury,  1917,  Bull.  Amer.  Paleon¬ 
tology,  vol.  5,  pp.  381-382,  plate  63,  fig.  5.  Olsson,  1922,  Bull.  Amer. 
Paleontology,  vol.  9,  p.  413,  plate  30,  figs.  5,  6. 

The  following  is  the  original  description  of  this  species: 

Suborbicular,  subequilateral,  moderately  convex,  adorned  with  numerous 
equidistant  lamellae,  between  each  of  which  there  are  about  7  or  8  concen¬ 
tric  striae;  somewhat  angulate  in  front  and  subtruncate  behind;  margins 
crenate.  Lunule  smooth,  impressed.  Posterior  dorsal  area  not  defined, 
striae  continuously  with  the  lamellae  of  the  disk.  Umbones  small.  Cardinal 
teeth  2  under  the  lunule;  lateral  tooth  1,  nearly  halfway  down  the  posterior 
slope. 

Type  locality . — Dominican  Republic. 

The  following  is  a  description  of  Bowden  specimens  of  this  species: 

Shell  moderately  large,  ovate,  very  inequilateral,  strongly  inflated; 
anterior  dorsal  margin  short,  slightly  excavated,  rounding  abruptly  into 
extended  anterior  end;  posterior  dorsal  margin  much  longer,  convex;  pos¬ 
terior  end  almost  vertically  truncate;  base  decidedly  arcuate;  umbos  full, 
strongly  prosogyrate;  lunule  large,  bounded  by  a  deep  groove;  escutcheon 
flattened,  limited  by  a  broad  fold;  sculpture  consisting  of  prominent 
recurved  concentric  lamellae,  suppressed  toward  escutcheon,  terminating  at 
the  boundaries  of  escutcheon  and  lunule,  but  continuing  across  them  as 
incrementals ;  3  to  7,  the  number  increasing  on  the  umbo,  finer  secondary 
lamellae  lie  between  the  primaries;  hinge  as  described  for  the  section. 

Length  44.5  mm.;  height  37  mm.;  diameter  (right  valve)  15  mm. 

This  species  is  distinguished  from  the  other  veneroids  by  the  promi¬ 
nent  primary  and  secondary  concentric  lamellae.  Adult  shells  are 
more  elongate  than  young  ones,  and  have  thicker  primary  concentric 
lamellae  and  few  secondary  lamellae  toward  the  ventral  margin.  On 
the  largest  shells  an  obscure  ridge,  at  which  the  primary  lamellae  are 


158 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


reduced,  is  visible  a  short  distance  from  the  ridge  bounding  the  escut¬ 
cheon. 

The  holotype  of  this  species  was  collected  at  an  unknown  locality 
in  the  Dominican  Republic.  Later  collections  show  that  it  is  con¬ 
fined  to  the  Gurabo  formation.  Bowden  specimens  are  slightly  less 
inflated  and  have  lower  and  less  inflated  umbos.  A  broken  valve  from 
Curagao  seems  to  be  this  species.  Olsson  has  described  specimens 
from  Costa  Rica. 

Broken  valves  from  the  Chipola  formation  of  Florida  have  the  same 
type  of  sculpture,  but  seem  to  be  more  rounded  and  less  inflated.  They 
probably  belong  to  a  different  species  represented  by  more  complete, 
but  poorly  preserved,  specimens  from  White  Beach,  Florida. 

Other  localities. — Gurabo  formation  (middle  Miocene),  Dominican 
Republic,  middle  (?)  Miocene,  Curagao,1  Gatun  formation  (middle 
Miocene),  Costa  Rica. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
115548). 

Genus  CYCLINELLA  Dali. 

Dali,  1902,  The  Nautilus,  vol.  16,  p.  44. 

Type  (by  subsequent  designation,  Dali,  1902,  Proc.  U .  S.  Nat. 
Mus.,  vol.  26,  p.  357). — Dosinia  tenuis  Recluz.  Recent,  West  Indies. 

The  following  is  a  description  of  the  genus  Cyclinella: 

Shell  medium-sized,  thin,  suborbicular;  lunule  and  escutcheon  absent; 
sculpture  consisting  of  incrementals ;  hinge  of  each  valve  consisting  of  3 
slender  cardinals  (3a,  1,  36;  2a,  26,  46),  the  right  posterior  one  (36)  deeply 
bifid;  pallial  sinus  moderately  wide  and  deep,  steeply  ascending,  the  apex 
narrowly  U-shaped. 

Cyclinella  is  the  American  representative  of  the  European  genus 
Mysia  (called  Lucinopsis  by  some  writers),  the  right  valve  of  which 
has  only  2  cardinals.  Guppy  has  described  a  species,  Dosinia  cyclica, 
from  deposits  of  so-called  Eocene  age  at  Manzanilla,  Trinidad.  These 
deposits  probably  are  Miocene.  Aside  from  this  doubtful  record,  the 
earliest  species  is  of  Miocene  age. 

Cyclinella  plasiatenuis,  new  species. 

(Plate  21,  Figures  10,  11.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  thin,  suborbicular,  subequilateral,  moderately  in¬ 
flated;  dorsal  margins  rounding  evenly  into  lateral  margins;  anterior  end 
slightly  more  extended  than  posterior;  umbo  full,  strongly  incurved,  mod¬ 
erately  high;  sculpture  consisting  of  irregular  incrementals. 

Length  24  mm.;  height  24  mm.;  diameter  (left  valve)  8mm. 

C.  plasiatenuis  is  known  only  from  the  holotype,  an  incomplete  left 
valve.  Only  part  of  the  lunule  is  preserved,  but  it  apparently  is  rela- 


1  See  footnote  on  page  25. 


PELECYPODS. 


159 


tively  large  and  limited  by  a  shallow  groove.  This  species  closely 
resembles  the  larger  living  C.  tenuis  (Recluz),  but  is  more  orbicular 
and  has  slightly  more  compressed  teeth.  C.  cyclica  (Guppy),  a  Mio¬ 
cene  (?)  species  from  Manzanilla,  Trinidad,  and  C.  gatunensis  Dali, 
from  the  Gatun  formation,  are  larger  and  less  orbicular.  C.  plasi - 
atenuis  more  closely  resembles  C.  beteyensis  Olsson,1  a  Miocene 
species  from  Costa  Rica,  but  is  smaller  and  more  inflated. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352834). 

Genus  CHIONE  Megerle  von  Miihlfeld. 

Subgenus  CHIONE  s.  s. 

Section  CHIONE  s.  s. 

Mergerle  von  Miihlfeld,  1811,  Gesellschaft  naturforschender  Freunde  zu  Berlin, 
Magazin  fur  die  neuesten  Entdeckungen  in  der  gesammten  Naturkunde, 
year  5,  p.  51. 

Type  (by  subsequent  designation ,  Gray,  181+7) . — Venus  dysera 
Chemnitz  ( =Venus  cancellata  Linne).  Recent,  West  Indies. 

The  following  is  a  description  of  the  section  Chione  s.  s. : 

Shell  medium-sized,  ovate,  strongly  inflated;  lunule  and  escutcheon  sepa¬ 
rated  by  absence  of  strong  sculpture;  sculpture  consisting  of  upturned  con¬ 
centric  lamellae,  frilled  by  narrow  radial  ribs;  hinge  of  right  valve  consist¬ 
ing  of  3  cardinals,  the  anterior  one  (3a)  slender,  the  others  (1,  3b)  heavy 
and  obscurely  bifid;  hinge  of  left  valve  consisting  of  3  cardinals,  the  middle 
one  (2b)  heavier  than  the  others  (2a,  4b)  and  having  2  obscure  grooves; 
pallial  sinus  very  shallow,  its  apex  broadly  V-shaped;  ventral  and  anterior 
inner  margins  fluted. 

Living  and  fossil  species  of  Chione  s.  s.  are  confined  to  the  West 
Indies,  adjoining  American  waters,  and  the  Pacific  Ocean.  The  genus, 
which  first  appears  in  lower  Miocene  time,  is  very  conspicuous  in 
American  tropical  and  subtropical  Miocene  and  Pliocene  faunas. 

Key  to  the  Bowden  species  of  Chione  s.  s. 

Radial  riba  obscure .  C.  (C.)  sawkinsi 

Radial  ribs  strong. 

Outline  trigonal-ovate .  C.  ( C .)  woodwardi 

Outline  elongate-ovate .  C.  ( C .)  retugida 

Chione  (Chione)  sawkinsi,  new  species. 

(Plate  21,  Figures  12  to  14.) 

Venus  woodwardi  Guppy,  1866  (part),  Quart.  Jour.  Geol.  Soc.  London,  vol. 
22,  p.  292,  not  plate  18,  fig.  1.  Guppy,  1874  (part),  Geol.  Mag.  decade  2, 
vol.  1,  p.  442  (list). 

Chione  woodwardi  (Guppy),  Dali,  1903  (part),  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  6,  pp.  1291-1292. 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  ovate-trigonal,  moderately  inequilateral,  strongly 
inflated;  lower  part  of  posterior  margin  obliquely  truncate;  lunule  limited 
by  a  deep  groove;  escutcheon  relatively  narrow,  bounded  by  a  rounded 
ridge;  margin  of  left  valve  adjacent  to  ligament  raised  along  proximal  two- 


1  Comparison  based  on  figures. 


160 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


thirds  of  its  length;  a  short  distance  from  this  ridge  lies  a  second  lower 
ridge,  which  disappears  toward  the  umbo,  area  between  the  two  ridges 
slightly  excavated  and  forming  at  margins  the  truncation;  sculpture  con¬ 
sisting  of  numerous  concentric  lamellae;  over  more  than  anterior  half  of 
shell  their  edges  are  thickened  and  turned  toward  the  umbo,  except  near 
the  lunule;  on  their  ventral  sides  are  low  radial  ribs,  separated  by  inter¬ 
spaces  of  varying  width;  the  ribs  fail  to  extend  across  the  interspaces,  but 
alternate  with  broader  and  less  distinct  ribs  on  the  shorter  dorsal  side  of 
the  lamellae;  behind  a  radial  line  near  middle  of  shell  the  edge  of  the 
lamellae  is  turned  toward  the  ventral  margin  and  is  finely  frilled;  from 
the  ends  of  each  frill  narrow  low  radials  extend  across  at  least  the  dorsal 
half  of  the  interspaces;  right  anterior  cardinal  (3a)  heavy,  right  middle 
cardinal  (1)  slender,  right  posterior  cardinal  (36)  distinctly  bifid;  left 
middle  cardinal  (26)  distinctly  bifid;  flutings  of  inner  margin  fine. 

Length  25.5  mm.;  height  22  mm.;  diameter  (right  valve)  8  mm. 

This  species  is  one  of  the  most  abundant  veneroids.  Young  shells 
are  more  rounded  and  their  concentric  lamellae  may  be  frilled  over 
the  entire  shell.  The  slight  posterior  truncation  and  the  expanding 
and  frilling  of  the  concentric  lamellae  on  the  posterior  half  of  the 
shell  are  characteristic  features.  The  largest  specimen  has  the  follow¬ 
ing  dimensions:  length  33.8  mm.;  height  28  mm.;  diameter  (right 
valve)  8.5  mm. 

Although  the  type  of  Venus  woodwardi  is  in  the  British  Museum, 
7  specimens  in  the  Guppy  collection  (U.  S.  Nat.  Mus.  No.  115545)  are 
labeled  “types.”  All  these  shells  represent  the  species  here  described 
as  Chione  sawkinsi.  The  same  species  is  represented  by  a  few  speci¬ 
mens  from  the  Cercado  formation  of  the  Dominican  Republic  that 
have  fewer  and  coarser  lamellae.  C.  walli  (Guppy),  from  Trinidad, 
and  C.  guppyana  Gabb,  from  the  Dominican  Republic,  have  more  ribs 
on  the  ventral  face  of  the  lamellae  than  in  the  interspaces. 

Other  localities. — Cercado  formation  (lower  Miocene),  Dominican 
Republic. 

Type  material. — Holotype  (U.  S.  Nat.  Mus.  No.  352836). 

Chione  (Chione)  woodwardi  (Guppy). 

(Plate  22,  Figures  1  to  4.) 

Venus  woodwardi  Guppy,  1866  (part),  Quart.  Jour.  Geol.  Soc.  London,  vol. 
22,  p.  292,  plate  18,  fig.  1.  Guppy,  1874  (part),  Geol.  Mag.,  decade  2,  vol. 
1,  p.  442  (list). 

Chione  woodward  (Guppy),  Dali,  1903  (part),  Trans.  Wagner  Free  Inst. 
Sci.  Philadelphia,  vol.  3,  part  6,  pp.  1291-1292.  Maury,  1917,  Bull.  Amer. 
Paleontology,  vol.  5,  p.  382,  plate  63,  fig.  6.  ?  Maury,  1920,  Scientific 

Survey  Porto  Rico  and  Virgin  Islands,  vol.  3,  part  1,  pp.  40-41,  New 
York  Acad.  Sci.  ?  Hubbard,  1921,  Scientific  Survey  Porto  Rico  and 
Virgin  Islands,  vol.  3,  part  2,  p.  122,  plate  13,  fig.  7,  New  York  Acad.  Sci. 
Not  Venus  woodwardi  Guppy,  1876,  Quart.  Jour.  Geol.  Soc.  London,  vol.  32, 
p.  530  C?=Chione  guppyana  Gabb). 

The  following  is  the  original  description  of  this  species: 

Shell  subtrigonal,  somewhat  inequilateral,  anteriorly  rounded,  posteriorly 
somewhat  angulated;  ornamented  with  numerous  fine  radiating  costellae, 


PELECYPODS. 


161 


interrupted  by  equidistant  concentric  crenulate  ridges,  which  are  continued 
across  the  large  lunule;  margin  beneath  the  lunule  internally  obsoletely 
toothed. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  medium-sized,  high,  rounded  trigonal;  lunule  large,  ornamented  by 
continuations  of  concentric  lamellae;  escutcheon  limited  by  an  angular 
ridge;  in  front  of  posterior  margin  on  ventral  part  of  shell  lies  an  obscure 
slightly  depressed  area,  causing  an  obscure  emargination  on  ventral  margin; 
sculpture  consisting  of  widely  spaced  concentric  lamellae,  frilled  by  strong 
radials  extending  across  interspaces;  the  concentric  ribs  extend  across  the 
lunule,  but  are  irregularly  frilled;  immediately  behind  lunule  both  radials 
and  interspaces  separating  them  are  relatively  broad;  toward  center  of 
shell  the  radials  retain  their  width  or  are  slightly  narrower,  but  the  inter¬ 
spaces  become  narrower;  the  concentric  lamellae  stop  abruptly  at  the  ridge 
bounding  the  escutcheon;  right  (3a)  and  left  (2a)  anterior  cardinals  parallel 
to  dorsal  margin  of  shell,  right  middle  cardinal  (1)  relatively  heavy;  fluting 
of  inner  margin  relatively  coarse. 

Length  21  mm.;  height  19.6  mm.;  diameter  (left  valve)  7  mm. 

The  ventral  posterior  depressed  area  and  accompanying  emargina¬ 
tion  of  the  ventral  margin  are  obscure  and  can  not  be  detected  on 
young  shells.  One  or  two  of  the  broad  anterior  radials  may  be 
grooved.  On  some  shells  reduced  concentric  lamellae  extend  across 
the  posterior  ridge,  and  may  even  continue  for  a  short  distance  across 
the  escutcheon. 

C.  woodwardi  has  stronger  and  coarser  radial  ribs  than  C.  sawkinsi 
and  its  concentric  lamellae  are  more  strongly  frilled.  Specimens  from 
the  Cercado  formation  of  the  Dominican  Republic  have  slightly  nar¬ 
rower  ribs.  Impressions  of  a  Chione  from  the  Quebradillas  limestone 
of  Porto  Rico  were  called  C.  woodwardi  by  Maury  and  Hubbard. 
C.  woodwardi  closely  resembles  C.  tegulum  Brown  and  Pilsbry,  from 
the  Gatun  formation,  but  is  less  inflated,  and  has  a  more  extended 
posterior  end  and  more  extended  concentric  lamellae.  It  also  resem¬ 
bles  the  living  C.  cancellata  (Linne),  but  is  smaller  and  has  more 
numerous  concentric  lamellae. 

Other  localities. — Cercado  formation  (lower  Miocene),  Dominican 
Republic. 

Type  material. — Holotype;  British  Museum  (Natural  History), 
Geological  Department,  No.  64084. 

Chione  (Chione)  retugida,  new  species. 

(Plate  22,  Figures  5,  6.) 

The  following  is  a  description  of  this  species: 

Shell  small,  moderately  inflated,  elongate-ovate;  groove  bounding  lunule 
shallow;  escutcheon  long  and  broad  for  size  of  shell,  proximal  half  of  its 
margin  adjacent  to  ligament  slightly  raised;  in  front  of  ridge  limiting 


162 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


escutcheon  surface  of  shell  slightly  depressed  toward  ventral  margin,  but 
not  enough  to  affect  margin;  sculpture  consisting  of  a  moderate  number 
of  concentric  lamellae  and  prominent  rounded  radials  crossing  the  inter¬ 
spaces;  near  the  lunule  the  edge  of  the  concentric  lamellae  are  turned 
toward  the  ventral  margin  and  slightly  frilled,  but  over  remainder  of 
anterior  two-thirds  of  shell  the  edge  is  turned  toward  the  umbo,  thickened 
and  the  frills  obscure  or  absent;  on  the  posterior  third,  the  edge  is  turned 
toward  the  ventral  margin  and  frilled ;  obscure  continuations  of  the  lamellae 
extend  across  the  lunule;  right  (3a)  and  left  (2a)  anterior  cardinal  parallel 
to  dorsal  margin  of  shell;  left  middle  cardinal  (26)  obscurely  bifid. 

Length  7  mm.;  height  5.5  mm.;  diameter  (left  valve)  1.5  mm. 

Most  of  the  valves  are  larger  than  the  holotype,  but  are  somewhat 
worn.  The  largest  has  the  following  dimensions:  length  9.8  mm.; 
height  7  mm.;  diameter  2.1  mm.  The  concentric  sculpture  resembles 
that  of  C.  sawkinsi.  As  in  C.  sawkinsi,  on  small  valves  all  the  lamellae 
are  frilled.  On  adult  valves  they  are  thickened  and  smooth  over  most 
of  the  anterior  two-thirds.  The  radial  ribs  are  similar  to  those  of 
C.  woodwardi. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352837). 

Section  LIROPHORA  Conrad. 

Conrad,  1863,  Proceedings  Academy  of  Natural  Sciences  Philadelphia  for 
1862,  pp.  575,  586. 

Type  (by  subsequent  designation,  Dali,  1902). — Circumphalus 
( Lirophora )  athleta  Conrad  (=Venus  latilirata  Conrad).  Miocene 
and  Pliocene,  middle  Atlantic  states. 

The  following  is  a  description  of  the  section  Lirophora: 

Shell  medium-sized,  trigonal-ovate;  lunule  limited  by  a  narrow  deep 
groove;  escutcheon  flattened;  sculpture  consisting  of  very  heavy  thickened 
concentric  lamellae;  hinge  of  each  valve  consisting  of  3  cardinals,  the  right 
anterior  one  (3a)  paralleling  dorsal  margin  of  shell,  the  right  middle  one 
(1)  subparallel  to  it,  the  left  anterior  one  (2a)  relatively  heavy,  the  upper 
face  of  left  middle  one  (26)  having  two  obscure  grooves;  right  nymph  and 
left  posterior  cardinal  (46)  roughened;  pallial  sinus  narrow,  shallow;  inner 
ventral  and  anterior  margins  finely  fluted. 

Aside  from  the  striking  difference  in  sculpture  Lirophora  differs 
from  Chione  s.  s.,  in  having  a  longer  right  anterior  cardinal  (3a),  more 
compressed  left  anterior  cardinal  (2a),  and  narrower  pallial  sinus. 

Externally  Lirophora  closely  resembles  some  of  the  European  Mio¬ 
cene  species  of  Clausinella,  but  has  a  wider  lunule  and  the  inner 
margin  of  the  lunule  is  frilled.  The  fossil  and  living  species  of  Liro¬ 
phora  are  confined  to  tropical  and  subtropical  parts  of  the  Atlantic 
and  Pacific  coasts  of  America.  There  are  many  species  in  the  late 
Tertiary  faunas  of  the  West  Indies  and  the  adjacent  mainland.  The 
earliest  species  is  recorded  from  the  Byram  marl  (upper  Oligocene)  of 
Mississippi  and  middle  Oligocene  beds  in  Porto  Rico. 


PELECYPODS. 


163 


Chione  (Lirophora)  hendersoni  Dali. 

(Plate  22,  Figures  7  to  10.) 

Venus  paphia  Guppy  (not  Linne),  1866,  Quart.  Jour.  Geol.  Soc.  London,  vol. 
22,  p.  292.  Guppy  (part,  not  Linne),  1874,  Geol.  Mag.,  decade  2,  vol.  1, 
p.  442  (list).  Guppy  (not  Linne),  1876,  Quart.  Jour.  Geol.  Soc.  London, 
vol.  32,  p.  530. 

Chione  paphia  Gabb  (not  Linne),  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol. 
15,  p.  249. 

Chione  ( Lirophora )  hendersonii  Dali,  1903,  Trans,  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  6,  pp.  1295-1296,  plate  55,  fig.  22.  Maury,  1917, 
Bull.  Amer.  Paleontology,  vol.  5,  p.  383,  plate  63,  figs.  8,  9.  ?Hubbard, 
1921,  Scientific  Survey  Porto  Rico  and  Virgin  Islands,  vol.  3,  part  2,  pp. 
122-123,  New  York  Acad.  Sci.  Not  Spieker,  1922,  Johns  Hopkins  Uni¬ 
versity  Studies  in  Geology,  No.  3,  pp.  154-155. 

Chione  ( Lirophora )  paphia  Pilsbry  (not  Linne),  1922,  Proc.  Acad.  Nat.  Sci. 
Philadelphia,  vol.  73,  p.  423. 

The  following  is  the  original  description  of  this  species : 

Shell  resembling  the  last  species  (C.  ballista  Dali),  but  with  about  15 
ribs,  on  the  ventral  bases  of  which  the  radial  sculpture  is  represented  by  a 
series  of  punctuations  which  are  rarely  drawn  out  into  striae;  the  ribs 
are  closer  together,  sometimes  obscuring  the  interspaces;  the  imaginary  line 
at  which  the  thick  ribs  suddenly  become  very  thin  and  elevated  marks  off 
the  posterior  third  of  the  shell,  more  than  in  any  other  species  noted;  the 
foliations  are  very  thin  and  were  presumably  elevated,  but  are  destroyed 
in  all  the  specimens  examined.  In  harmony  with  this  arrangement  of  the 
sculpture  the  posterior  end  of  the  shell  is  somewhat  rostrate ;  the  lunule  and 
escutcheon  are  wider  than  in  C.  ballista;  the  hinge  normal,  the  teeth  entire, 
the  pallial  sinus  small  and  angular,  and  the  adductor  scars  subequal. 

Length  of  an  average  specimen  27.5,  height  20.5,  diameter  14.0  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  medium-sized,  ovate-trigonal;  lunule  deeply  depressed;  escutcheon 
broad,  bounded  by  a  distinct  ridge;  sculpture  consisting  of  15  to  22  con¬ 
centric  lamellae,  all  except  those  on  tip  of  umbo  thickened  and  bent  upward; 
along  a  radial  line  about  three-fourths  of  distance  from  anterior  end,  edges 
of  lamellae  become  thinner  and  continue  to  ridge  bounding  escutcheon; 
on  this  part  of  the  shell  the  lamellae  usually  are  broken;  at  anterior  end 
the  lamellae  abruptly  stop  a  short  distance  from  narrow  groove  limiting 
lunule;  ventral  base  of  ribs  obscurely  or  distinctly  punctuate;  between  the 
ribs  are  incrementals  that  become  more  prominent  toward  anterior  and 
posterior  ends,  and  extend  across  lunule  and  escutcheon. 

Length  33.5  mm.;  height  27.5  mm.;  diameter  (left  valve)  9  mm. 

C.  hendersoni  is  the  most  abundant  veneroid.  Some  valves  are 
more  convex  than  others  and  have  higher  umbos,  steeper  posterior 
slope,  more  excavated  anterior  margin,  and  wider  lunule  and  escut¬ 
cheon.  The  average  number  of  lamellae  is  16  to  18.  When  the  inter¬ 
spaces  are  wide,  as  a  result  of  the  reduction  in  the  number  of  lamellae, 
1  or  2  of  the  incrementals  in  the  interspaces  near  the  ventral  margin 
may  be  emphasized. 


164 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  relatively  large  posterior  area,  over  which  the  lamellae  are  thin- 
edged,  is  a  characteristic  feature.  The  contrast  between  the  lamellae 
on  this  posterior  area  and  on  the  rest  of  the  shell  is  striking,  as  the 
thin-edged  lamellae  usually  are  broken.  A  small  valve  from  the 
Cercado  formation  of  the  Dominican  Republic  seems  to  be  this  species. 
Specimens  from  the  Gurabo  formation  are  a  little  more  elongate  than 
jBowden  specimens,  and  have  a  slightly  wider  lunule  that  is  more 
deeply  depressed  near  its  edge,  shorter  left  anterior  cardinal,  and  more 
slender  right  anterior  cardinal.  Hubbard  records  this  species  from 
middle  Oligocene  beds  in  Porto  Rico,  but  no  figures  are  given.  The 
Chione  from  the  Zorritos  formation  of  Peru,  described  by  Spieker,  is 
larger,  less  elongate,  and  has  a  shallower  lunule  and  cruder  sculpture. 

There  are  several  similar  American  Tertiary  species,  for  example, 
C.  ballista  Dali  from  the  Tampa  formation  of  Florida,  and  C.  glyp- 
tocyma  Dali  from  the  Oak  Grove  sand  of  Florida.  The  living  West 
Indian  species  C.  paphia  (Linne)  reaches  a  larger  size,  and  has  a  more 
arcuate  base  and  more  closely  appressed  lamellae. 

Other  localities. — Cercado  (lower  Miocene),  and  Gurabo  (middle 
Miocene)  formation,  Dominican  Republic. 

Type  material. — 5  cotypes  (U.  S.  Nat.  Mus.  No.  115543). 

Genus  PARASTARTE  Conrad. 

Conrad,  1863,  Proceedings  Academy  Natural  Sciences  Philadelphia  for  1862, 

p.  288. 

Type  {by  original  designation). — Astarte  triquetra  Conrad.  Mio¬ 
cene  to  Recent,  Florida. 

The  following  is  a  description  of  the  genus  Par  astarte: 

Shell  small,  trigonal-equilateral;  umbos  narrow;  lunule  large,  not  de¬ 
pressed,  obscurely  limited;  escutcheon  absent;  sculpture  consisting  of  incre- 
mentals;  hinge  of  right  valve  consisting  of  a  heavy  middle  cardinal  (1), 
and  small,  slender  anterior  (3a)  and  posterior  (35)  cardinals;  hinge  of 
left  valve  consisting  of  obscurely  bifid  anterior  (2)  and  posterior  (45) 
cardinals;  ligaments  short;  posterior  end  of  pallial  line  flexed,  but  there 
is  no  distinct  pallial  sinus;  inner  ventral  margin  of  valve  finely  fluted. 

Parastarte  triquetra  is  the  only  species  of  the  genus  heretofore 
described.  It  occurs  in  the  Miocene  and  Pliocene  deposits  of  Florida, 
and  is  living  along  the  east  and  west  coasts  of  Florida. 

Parastarte  antillensis,  new  species. 

(Plate  22,  Figures  11,  12.) 

The  following  is  a  description  of  this  species: 

Shell  small,  narrow,  high,  trigonal,  strongly  inflated,  subequilateral, 
anterior  end  slightly  more  extended;  umbo  high,  full,  slightly  prosogyrate; 
sculpture  consisting  of  incrementals ;  hinge  of  left  valve  consisting  of  2 
strong  faintly  bifid  cardinals  (2  and  45),  separated  by  a  relatively  broad 
and  deep  socket;  inner  margin  of  valve  finely  fluted,  right  valve  not  known. 

Length  3.5  mm.;  height  3.8  mm.;  diameter  (left  valve)  1.5  mm. 


PELECYPODS. 


165 


Parastarte  antillensis  closely  resembles  P.  triquetra  Conrad,  but  is 
slightly  larger  and  broader,  and  the  apex  of  its  umbo  is  narrower.  It 
is  known  only  from  the  holotype.  There  is  a  possibility  that  it  is  not 
a  Bowden  shell. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352839). 

Family  COOPERELLIDAE. 

Genus  COOPERELLA  Carpenter. 

Subgenus  COOPERELLA  s.  s. 

Carpenter,  1864,  Report  British  Association  for  Advancement  of  Science  for 
1863,  pp.  611,  639. 

Type  ( by  monotypy) . — Oedalia  ( Cooperella )  scintillaeformis  Car¬ 
penter  ( =Oedalia  subdiaphiana  Carpenter).  Pleistocene  and  Recent, 
California. 

The  following  is  a  description  of  the  subgenus  Cooperella  s.  s. : 

Shell  small,  thin,  ovate,  moderately  inequilateral,  moderately  inflated; 
hinge  of  right  valve  consisting  of  2  thin  cardinals  (3a  and  36),  the  posterior 
one  (36)  bifid;  hinge  of  left  valve  consisting  of  3  thin  cardinals  (2a,  26,  46), 
the  middle  one  (26)  divided  to  form  an  inverted  ;  resilium  seated  on  a 
narrow  depressed  area  behind  cardinals  and  separated  from  them  by  a  thin 
plate;  pallial  sinus  deep,  wide,  its  apex  y-shaped. 

The  living  species  of  Cooperella  s.  s.  are  confined  to  the  Pacific  coast 
of  America,  but  Dali  has  described  a  Miocene  species  from  the  middle 
Atlantic  states. 


Subgenus  COOPERELLOPSIS,  new  subgenus. 

Type . — Cooperella  (Cooper ellopsis)  thaumasta,  new  species. 

The  following  is  a  description  of  the  subgenus  Cooper  ellopsis: 

Shell  small,  thin,  subequilateral,  subrectangular,  strongly  inflated;  umbos 
high,  wide;  sculpture  consisting  of  incrementals ;  hinge  of  left  valve  resem¬ 
bling  Cooperella  s.  s.,  but  the  middle  cardinal  (26)  is  obscurely  bifid;  pallial 
sinus  obscure ;  right  valve  not  known. 

Aside  from  the  striking  difference  in  outline  Cooperellopsis  differs 
from  Cooperella  s.  s.  in  having  an  obscurely  bifid,  instead  of  deeply 
bifid,  left  middle  cardinal  (2b). 

Cooperella  (Cooperellopsis)  thaumasta,  new  species. 

(Plate  22,  Figures  13  to  15.) 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  rounded  subquadrate,  subequilateral,  greatly  inflated; 
anterior  margin  broadly  rounded,  posterior  margin  obliquely  subtruncate, 
median  part  of  base  almost  straight;  umbo  high,  broad,  full;  surface  bearing 
a  few  obscure  irregularly  spaced  incrementals ;  ligament  area  short,  resilium 
area  short,  moderately  depressed,  largely  external,  both  placed  behind 
cardinals;  hinge  of  left  valve  consisting  of  3  diverging  cardinals,  anterior 
(2a)  and  posterior  (46)  ones  compressed,  middle  one  (26)  larger,  triangular 
and  obscurely  bifid ;  pallial  sinus  obscure ;  right  valve  not  known. 

Length  7.5  mm.;  height  7.2  mm.;  diameter  (left  valve)  3.5  mm. 


166 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


This  species,  which  is  represented  by  the  holotype,  a  left  valve,  is 
remarkable  for  its  extreme  inflation,  the  diameter  almost  equaling 
the  length  or  height. 

Type  material. — Holotype  (left  valve,  U.  S,  Nat.  Mus.  No.  352840). 

Superfamily  TELLINACEA. 

Family  TELLINIDAE. 

Genus  TELLINA  Linne. 

Subgenus  TELLINA  s.  s. 

Section  TELLINA  s.  s. 

Linne,  1758,  Systema  Naturae,  ed.  10,  p.  674. 

Type  ( by  subsequent  designation,  Gray,  181+7). — Tellina  radiata 
Linne.  Recent,  West  Indies. 

The  following  is  a  description  of  the  section  Tellina  s.  s. : 

Shell  relatively  large,  elongate-ovate;  base  emarginate  near  posterior 
end,  a  shallow  depression  extending  from  the  emargination  toward  the 
umbo;  sculpture  consisting  of  incrementals  and  obscure  radial  markings; 
hinge  of  right  valve  consisting  of  a  slender  anterior  cardinal  (3a),  a  heavy 
bifid  posterior  cardinal  (36),  and  distinct  anterior  and  posterior  lateral 
lamellae;  hinge  of  left  valve  consisting  of  a  deeply  bifid  anterior  cardinal 
(2),  a  smaller  posterior  cardinal  (4),  and  obscure  anterior  and  posterior 
lateral  lamellae;  pallial  sinus  extraordinarily  deep,  its  apex  asymmetrically 
U  -shaped,  almost  touching  anterior  muscle-scar,  confluent  with  pallial  line, 
lower  limb  of  sinus  joining  pallial  line  at  middle  of  shell. 

Tellina  virgata  Linne  usually  is  given  as  the  type  species  because 
it  is  the  only  species  listed  by  Lamarck  in  the  Prodrome.  Tellinas 
of  the  group  of  T.  radiata  are  called  Liotellina  Fischer,  which  has  the 
same  type. 

There  are  no  species  of  Tellina  s.  s.  in  the  Bowden  formation. 

Section  MOERELLA  Fischer. 

Fischer,  1887,  Manuel  de  Conchyliologie,  p.  1147. 

Type  (by  monotypy). — Tellina  donacina  Linne.  Recent,  seas  of 
Europe. 

The  following  is  a  description  of  the  section  Moerella: 

Shell  medium-sized,  inflated,  elongate-ovate,  inequilateral,  posterior  end 
obscurely  rostrate;  sculpture  consisting  of  concentric  rugae;  right  anterior 
(3a)  and  left  posterior  (4)  cardinals  very  small;  right  laterals  strong, 
anterior  one  closer  to  cardinals;  left  laterals  weaker,  anterior  one  weaker 
than  posterior;  pallial  sinus  almost  touching  anterior  adductor  scar,  con¬ 
fluent  with  pallial  line,  its  apex  U-shaped. 

The  left  anterior  lateral  is  weaker  than  in  Tellina  s.  s.  The  Tertiary 
and  living  species  of  Moerella,  all  of  which  are  relatively  small,  are 
widely  distributed. 

Key  to  the  Bowden  species  of  Moerella. 

Posterior  end  obscurely  rostrate 
Posterior  end  not  rostrate . 


.  T.  ( M .)  simpsoni 
T.  (M.)  hendersoni 


PELECYPODS. 


167 


Tellina  (Moerella)  simpsoni  Dali. 

(Plate  23,  Figures  1  to  3.) 

Tellina  ( Moerella )  simpsoni  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  5,  p.  1024,  plate  46,  fig.  12. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  inflated,  equivalve,  very  inequilateral,  polished;  anterior 
dorsal  slope  rectilinear,  anterior  end  rounded,  base  convexly  arcuate; 
posterior  end  very  short  with  the  extremity  bluntly  pointed;  beaks  low, 
somewhat  opisthogyrous,  with  a  perceptible  lunule;  hinge  normal,  pallial 
sinus  extending  nearly  to  the  anterior  adductor  scar,  mostly  confluent  below. 
Long.  7,  alt.  5,  diam.  4  mm. 

Type  locality. — Bowden,  Jamaica. 

T.  ( M .)  simpsoni  is  distinguished  by  its  very  inequilateral  outline, 
convexity  and  slight  posterior  rostrum.  Some  valves  are  sculptured 
with  fine  concentric  striae. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135697). 

Tellina  (Moerella)  hendersoni  Dali. 

(Plate  23,  Figures  4  to  7.) 

Tellina  ( Moerella )  hendersoni  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  5,  pp.  1024-1025,  plate  46,  fig.  5. 

r 

The  following  is  the  original  description  of  this  species : 

Shell  small,  moderately  convex,  very  inequilateral;  resembling  the  pre¬ 
ceding  species  T.  simpsoni  but  less  inflated,  more  regular,  with  posterior 
end  not  constricted  or  markedly  flexed;  surface  polished,  with,  except  near 
the  beaks,  fine,  rather  distant,  concentric  threads,  which  on  the  basal  half 
of  the  posterior  end  rise  into  extremely  delicate  low  lamellae;  hinge  normal, 
strong;  pallial  sinus  connecting  the  adductor  scars  and  confluent  below; 
there  is  a  slightly  impressed  narrow  lunule.  Lon.  7.5,  alt.  4,  diam.  3  mm. 

Type  locality. — Bowden,  Jamaica. 

This  species,  which  is  abundant,  closely  resembles  T.  simpsoni,  but 
its  posterior  end  is  not  rostrate.  One  of  the  largest  valves  of  T.  hen¬ 
dersoni  has  the  following  dimensions:  length  8  mm.;  height  6  mm.; 
diameter  2  mm.  The  largest  valve  of  T.  simpsoni  has  the  following 
dimensions:  length  6.5  mm.;  height  5  mm.;  diameter  2  mm.  Most 
valves  of  T.  hendersoni  are  less  inflated  than  those  of  T.  simpsoni,  but 
some  are  as  strongly  inflated.  T.  aclontea  Dali,  from  the  Chipola  for¬ 
mation  of  Florida,  is  smaller,  less  inflated,  and  more  elongate. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135696). 

Section  EURYTELLINA  Fischer. 

Fischer,  1887,  Manuel  de  Conchyliologie,  p.  1147. 

Type  (by  monotypy). — Tellina  punicea  Born.  Recent,  Pacific 
coast  of  northern  South  America. 


168 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  following  is  a  description  of  the  section  Eurytellina: 

Shell  medium-sized,  elongate-ovate,  subequilateral ;  posterior  end  not 
rostrate,  but  a  narrow  flattened  area  lies  at  the  posterior  end;  sculpture 
consisting  of  concentric  rugae;  right  anterior  cardinal  (3a)  relatively 
heavy,  right  laterals  strong,  anterior  one  close  to  the  cardinals,  posterior 
one  distant;  left  posterior  cardinal  (4)  small  and  very  slender,  left  laterals 
not  so  strong  as  right  ones,  resembling  them  in  position;  pallial  sinus 
touching  anterior  adductor,  wholly  confluent  with  pallial  line. 

The  small,  slender  left  posterior  cardinal  (4)  and  the  position  of 
the  laterals  are  characteristic  features  of  this  section,  which  is  exten¬ 
sively  represented  in  Tertiary  and  present  faunas. 

Key  to  the  Bowden  species  of  Eurytellina. 


Nymph  relatively  short,  thick. 

Length  exceeding  10  mm. 

Shell  heavy,  sculpture  strong .  T.  ( E .)  species 

Shell  thin,  sculpture  weak .  T.  ( E .)  spiekeri 

Length  not  exceeding  8  mm. 

Shell  distinctly  rostrate .  T.  (E.)  pharicda 

Shell  not  distinctly  rostrate .  T.  (E.)  gonida 

Nymph  long,  slender. 

Shell  subequilateral,  moderately  inflated .  T.  (E.)  halistrepta 

Shell  inequilateral,  strongly  inflated 

Shell  distinctly  rostrate .  T.  ( E .)  apomsa 

Shell  not  distinctly  rostrate .  T.  (E.)  browni 


Tellina  (Eurytellina)  species. 

(Plate  23,  Figures  8,  9.) 

Tellina  ( Eurytellina )  sp.,  Dali,  1900  (part),  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  5,  p.  1024. 

Two  broken  right  valves  in  the  U.  S.  National  Museum  collection 
represent  a  medium-sized  Eurytellina.  The  most  striking  feature  of 
this  species  is  the  short,  thick  nymph,  which  ends  abruptly  at  its 
posterior  end,  thus  affecting  the  outline  of  the  dorsal  margin. 

Spieker  considered  T.  aequicincta  Spieker,  from  the  Zorritos  forma¬ 
tion  of  Peru,  the  same  species.  The  holotype  from  Zorritos  has  a 
slender  nymph,  and  the  concentric  rugae  at  the  posterior  end  are  less 
foliaceous.  Specimens  from  Bowden  and  Zorritos  have  essentially 
the  same  outline  and  the  same  plan  of  sculpture. 

Tellina  (Eurytellina)  spiekeri,  new  species. 

(Plate  23,  Figures  10,  11.) 

Tellina  ( Angulus )  pressa  Dali,  1900  (part),  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  5,  p.  1026. 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  moderately  inflated,  inequilateral,  posterior  end  not 
rostrate;  sculpture  consisting  of  obscure  concentric  rugae;  nymph  short, 
thick ;  right  anterior  lateral  stronger  than  posterior  and  closer  to  cardinals ; 
hinge  of  left  valve  not  known;  pallial  sinus  touching  anterior  adductor 
scar,  wholly  confluent  with  pallial  line. 

Length  11.5  mm.;  height  6.5  mm.;  diameter  (right  valve)  1.5  mm. 

This  species  closely  resembles  T.  pressa  Dali,  from  the  Chipola  for¬ 
mation  of  Florida,  but  has  less  distinct  sculpture.  The  Tellina  from 


PELECYPODS. 


169 


the  Zorritos  formation  of  Peru  called  T.  pressa  by  Spieker  has  a  more 
slender  nymph,  shorter  right  anterior  lateral,  and  stronger  sculpture. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352843). 

Tellina  (Eurytellina)  pharcida  Dali. 

(Plate  23,  Figures  12  to  15.) 

Tellina  ( Angulus )  pharcida  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  5,  p.  1025,  plate  46,  fig.  7. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  elongate,  very  inequilateral,  moderately  convex;  anterior 
end  produced,  rounded;  posterior  end  short,  roundly  pointed,  with  a  slight 
flexure;  beaks  in  the  posterior  third;  surface  covered  with  extremely  fine 
close-set  grooves;  sculpture  as  usual  a  little  stronger  near  the  posterior 
end;  beaks  low,  pointed;  lunule  obsolete;  hinge  normal,  pallial  sinus  obscure 
in  the  polish  of  the  interior  but  probably  normal;  no  thickened  rays.  Lon. 
5.5,  alt.  3,  diam.  1.5  mm. 

Type  locality . — Bowden,  Jamaica. 

This  species  has  a  distinct  right  posterior  lateral  and  therefore  is 
not  an  Angulus  (type,  Tellina  lanceolata  Linne).  Its  long  right 
anterior  lateral  close  to  the  cardinals,  and  its  very  small  left  anterior 
cardinal  suggest  that  it  is  a  small  Eurytellina ,  although  it  is  more 
inequilateral  than  the  type  species,  and  its  posterior  end  is  clearly 
rostrate.  The  nymph  is  short  and  thick. 

It  resembles  the  Miocene  and  Pliocene  species  T.  umbra  Dali,  but 
is  smaller  and  more  inflated. 

Type  material.-— Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135706). 

Tellina  (Eurytellina)  gonida,  new  species. 

(Plate  23,  Figured  16,  17.) 

The  following  is  a  description  of  this  species: 

Shell  small,  elongate,  uniformly  inflated,  very  inequilateral;  posterior 
rostrum  scarcely  differentiated  from  general  convexity  of  shell;  sculpture 
consisting  of  fine  concentric  rugae,  some  of  which  are  slightly  lamellar  at 
posterior  end;  laterals  absent  on  left  valve,  left  posterior  cardinal  (4)  very 
small;  nymph  short,  thick;  pallial  sinus  obscure;  right  valve  not  known. 

Length  7.5  mm.;  height  4.5  mm.;  diameter  (left  valve)  1.7  mm. 

Although  this  species  has  no  recognizable  left  laterals  it  seems  to 
be  a  Eurytellina.  It  is  very  similar  to  T.  pharcida  Dali,  but  is  slightly 
higher  and  has  no  distinct  posterior  rostrum. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352844). 

Tellina  (Eurytellina)  halistrepta  Dali. 

(Plate  23,  Figure  18.) 

Tellina  ( Phyllodina )  halistrepta  Dali,  1900,  Trans.  Wagner  Free .  Inst.  Sci. 
Philadelphia,  vol.  3,  part  5,  p.  1023,  plate  47,  fig.  17. 

The  following  is  the  original  description  of  this  species: 

Shell  compressed,  flattish,  subequilateral,  longer  than  high;  beaks  small, 
low,  resembling  a  pustule  on  the  summit  of  the  broad  smooth  nepionic 


170 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


shell;  surface  marked  anteriorly  with  rather  close,  low,  elevated,  concentric 
threads  with  about  equal  interspaces;  near  the  posterior  third  of  the  disk 
these  threads  become  less  numerous  by  the  cessation  of  alternate  threads, 
making  the  interspaces  wider,  while  the  persistent  threads  become  lamellose; 
in  the  type,  which  is  a  young  shell,  the  dorsal  margin  is  not  coronate,  but 
in  the  adult  there  are  probably  dorsal  scales  corresponding  to  the  later 
lamellae;  hinge  normal  for  the  section,  pallial  line  obscure.  Lon.  9,  alt.  5.5, 
diam.  1.2  mm. 

Type  locality. — Bowden,  Jamaica. 

The  holotype,  a  right  valve,  is  the  only  specimen  of  this  species.  It 
lacks  the  sculpture  and  narrow  depressed  posterior  area  of  Phyllodina 
(type,  Tellina  squamijera  Deshayes).  Phyllodina  has  no  recognizable 
left  posterior  lateral ;  its  pallial  sinus  is  free  and  ascending,  resembling 
that  of  Arcopagia  (type,  Tellina  crassa  Pennant).  Cossmann  con¬ 
siders  Arcopagia  a  separate  genus  on  account  of  its  free  ascending 
pallial  sinus.  T.  halistrepta  probably  is  a  Eurytellina.  The  holotype 
is  glued  on  a  card  and  its  interior  is  inaccessible. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 

135704). 

Tellina  (Eurytellina)  apomsa,  new  species. 

(Plate  23,  Figures  19,  20.) 

The  following  is  a  description  of  this  species: 

Shell  small,  elongate,  moderately  inflated,  very  inequilateral;  posterior 
end  distinctly  rostrate,  area  in  front  of  it  slightly  depressed,  obscurely 
emarginating  base;  sculpture  consisting  of  concentric  rugae,  becoming 
slightly  lamellar  on  posterior  depressed  area;  right  posterior  lateral  weak; 
nymph  long,  slender;  pallial  sinus  obscure;  left  valve  not  known. 

Length  6  mm. ;  height  4  mm. ;  diameter  (right  valve)  1.2  mm. 

T.  ( E .)  apomsa  is  known  from  2  right  valves.  The  strong,  regular 
sculpture  is  the  most  characteristic  feature.  Aside  from  the  greater 
prominence  of  the  sculpture,  it  is  distinguished  from  T.  pharcida  and 
T.  gonida  by  its  greater  inflation,  greater  height,  less  extended  pos¬ 
terior  end,  stronger  rostrum,  and  longer  nymph. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 

352845). 

Tellina  (Eurytellina)  browni,  new  species. 

(Plate  23,  Figures  21,  22.) 

Tellina  ( Eurytellina )  sp.,  Dali,  1900  (part),  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  5,  p.  1024. 

The  following  is  a  description  of  this  species : 

Shell  small,  thin,  elongate,  moderately  inflated,  inequilateral;  posterior 
end  obscurely  rostrate,  a  broad  flattened  area  lies  behind  the  rostrum; 
sculpture  consisting  of  weak  concentric  rugae,  some  of  which  become 
lamellar  at  posterior  end;  right  laterals  strong;  the  left  valve  has  an 


PELECYPODS. 


171 


obscure  posterior  lateral,  but  no  anterior  one;  nymph  long,  slender;  pallial 
sinus  obscure. 

Length  7.8  mm.;  height  4.5  mm.;  diameter  (right  valve)  1.5  mm. 

This  species  is  represented  by  2  left  and  1  right  valve.  It  is  less 
inequilateral  than  T.  apomsa  and  has  no  distinct  rostrum.  Its  sculp¬ 
ture  is  similar  to  that  of  T.  halistrepta  Dali,  but  the  shell  is  more 
inequilateral  and  more  elongate. 

Type  material . — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352846). 

Section  MERISCA  Dali. 

Dali,  1900,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  290. 

Type  (by  original  designation) . — Tellina  crystallina  Wood.  Recent, 
West  Indies  and  Pacific  coast  of  Central  America. 

The  following  is  a  description  of  the  section  Merisca: 

Shell  small,  trigonal-ovate,  posterior  end  strongly  rostrate,  base  emargi- 
nate  in  front  of  rostrum;  sculpture  consisting  of  distant,  thin,  concentric 
lamellae;  hinge  resembling  Tellina  s.  s.,  but  the  left  laterals  are  absent; 
pallial  sinus  very  deep,  almost  touching  anterior  adductor  scar,  confluent 
with  pallial  line  along  virtually  its  entire  length. 

Merisca  is  separated  from  the  preceding  sections  by  the  absence  of 
left  laterals.  The  living  species  inhabit  the  warm-temperate  and 
tropical  seas. 

Key  to  the  Bowden  species  oj  Merisca. 


Shell  relatively  large,  length  exceeding  10  mm .  T.  ( M .)  species 

Shell  small,  length  less  than  10  mm. 

Radial  sculpture  absent .  T.  (Af.)  sclera 

Shell  moderately  inflated,  not  distinctly  rostrate .  T.  ( M .)  sclera  sclera 

Shell  strongly  inflated,  distinctly  rostrate .  T.  ( M .)  sclera  lerasca 

Radial  sculpture  present .  T.  ( M .)  acrocosmia 


Tellina  (Merisca)  species. 

Tellina  ( Merisca )  aequistriata  Dali,  1900  (part,  not  Say),  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  5,  p.  1020. 

Two  broken  right  valves  are  similar  to  the  Miocene  and  living 
species  Tellina  ( Merisca )  aequistriata  Say,  but  are  more  elongate  and 
more  inequilateral,  and  have  finer  sculpture  and  heavier  right  pos¬ 
terior  cardinal.  This  species  is  much  larger  than  the  other  Bowden 
species  of  Merisca. 

Tellina  (Merisca)  sclera  sclera  Dali. 

(Plate  24,  Figures  1  to  4.) 

Tellina  ( Merisca )  sclera  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia, 
vol.  3,  part  5,  p.  1021 ;  part  6,  plate  49,  fig.  5. 

The  following  is  the  original  description  of  this  subspecies: 

Shell  minute,  short,  plump,  with  low  inflated  beaks,  rounded  in  front  and 
below,  shorter  and  blunt  behind;  slightly  flexed,  not  rostrate,  but  with  an 


172 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


obsolete  radial  sulcus  in  the  right  valve;  sculpture  of  elevated  crowded 
concentric  threads,  becoming  alternately  obsolete  towards  the  ends  of  the 
shell  where  the  persistent  threads  are  more  elevated  and  tend  to  become 
lamellose;  hinge  normal,  strong  for  the  size  of  the  shell;  pallial  sinus  short, 
round,  confluent  below.  Lon.  4.2,  alt.  3.2,  diam.  2  mm. 

Type  locality. — Bowden,  Jamaica. 

The  largest  valve  has  the  following  dimensions:  length  5.2  mm.; 
height  3.8  mm.;  diameter  1.5  mm.  The  posterior  rostrum  is  obscure 
in  this  subspecies. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135698). 

Tellina  (Merisca)  sclera  lerasca,  new  subspecies. 

(Plate  24,  Figures  5,  6.) 

The  following  is  a  description  of  this  subspecies: 

Shell  small,  moderately  inequilateral,  greatly  inflated;  posterior  end 
obscurely  rostrate,  base  slightly  emarginate  in  front  of  rostrum;  umbo 
full,  low,  broad,  placed  nearer  posterior  end;  sculpture  as  in  T.  (M.)  sclera 
sclera ,  but  the  concentric  lamellae  are  less  conspicuous  near  the  posterior 
end;  hinge  heavy  for  size  of  shell. 

Length  5  mm.;  height  4  mm.;  diameter  (left  valve)  2  mm. 

The  left  valve  on  which  this  subspecies  is  based  is  much  more 
inflated  and  less  inequilateral  than  T .  sclera  sclera,  and  has  a  more 
distinct  posterior  rostrum. 

Type  material — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352848). 

Teflina  (Merisca)  acrocosmia  Dali. 

(Plate  24,  Figures  7  to  10.) 

Tellina  (Merisca?)  acrocosmia  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.  Phila¬ 
delphia,  vol.  3,  part  5,  pp.  1020-1021,  plate  46,  fig.  10. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  rounded,  triangular,  with  nearly  central  inconspicuous  beaks, 
and  hardly  pointed,  slightly  flexed,  posterior  end,  the  anterior  end  evenly 
rounded,  base  convexly  arched;  lunule  obsolete;  disk  covered  with  a  fine 
radial  threading,  more  or  less  concealed  by  fine,  elevated,  concentric  sharp 
lamellae;  hinge  normal,  teeth  large  and  strong  for  the  size  of  the  shell; 
pallial  sinus  large,  nearly  reaching  the  anterior  adductor  scar,  largely 
confluent  below;  above  rising  above  the  level  of  the  posterior  adductor. 
Lon.  7,  alt.  5.5,  diam.  3  mm. 

Type  locality. — Bowden,  Jamaica. 

This  species  is  one  of  the  most  abundant  species  of  Tellina.  The 
fine  radial  threads  frill  the  thin  concentric  lamellae.  The  posterior 
end  is  not  so  strongly  rostrate  as  in  the  type  species  of  the  section. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135699). 


PELECYPODS. 


173 


Section  SCISSULA  Dali. 

Dali,  1900,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  291. 

Type  (by  original  designation). — Tellina  decora  Say.  Recent, 
Florida. 

The  following  is  a  description  of  the  section  Scissula: 

Shell  medium-sized,  elongate  ovate,  moderately  inflated,  posterior  end 
not  distinctly  rostrate;  sculpture  consisting  of  concentric  rugae,  crossed 
by  oblique  rugae  in  central  part  of  shell,  at  the  posterior  end  the  rugae 
become  slightly  lamellar;  nymph  thick;  right  anterior  lateral  very  broad, 
bent  upward,  right  posterior  lateral  very  small,  much  farther  from  cardinals 
than  anterior  one;  left  posterior  lateral  small,  but  distinct,  anterior  one 
absent;  left  anterior  dorsal  margin  indented  opposite  right  anterior  lateral; 
pallial  sinus  almost  touching  anterior  adductor  scar,  confluent  with  pallial 
line,  its  apex  broadly  U-shaped. 

The  anterior  end  of  the  right  anterior  lateral  is  very  broad  and 
bent  upward  in  the  type  species.  The  position  of  the  right  laterals 
with  reference  to  the  cardinals  is  the  same  as  in  Eurytellina,  but  the 
posterior  one  is  much  less  distinct.  The  oblique  sculpture  is  a  striking 
feature. 

Fossil  and  living  species  of  Scissula  seem  to  be  confined  to  the  West 
Indies  and  adjoining  waters,  the  Pacific  coast  of  Central  and  southern 
North  America,  and  the  Pacific.  The  earliest  American  species  is  of 
lower  Miocene  age. 

Tellina  (Scissula)  healyi,  new  name. 

(Plate  24,  Figures  11  to  13.) 

Tellina  ( Scissula )  scitvla  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia, 
vol.  3,  part  5,  p.  1028,  plate  47,  fig.  15.  Maury,  1917,  Bull.  Amer.  Paleon¬ 
tology,  vol.  5,  p.  389,  plate  64,  fig.  12. 

Not  Tellina  scitula  Meek  and  Hayden,  1857,  Proc.  Acad.  Nat.  Sci.  Philadelphia 
for  1856,  p.  82. 

The  following  is  the  original  description  of  this  species : 

Shell  small,  thin,  elongate-ovate,  polished,  inequilateral;  rounded  in 
front,  moderately  pointed  behind;  beaks  low,  surface  with  fine,  regular, 
rather  close  striae  extending  obliquely  backward  towards  the  base,  with 
more  or  less  evident  microscopic  radial  striation;  posterior  dorsal  areas 
minutely  concentrically  waved;  interior  with  no  thickened  rays;  hinge 
normal,  very  delicate;  pallial  sinus  long,  high,  normal.  Lon.  8,  alt.  4.2, 
diam.  1.5  mm. 

Type  locality. — Bowden,  Jamaica. 

This  small  species  resembles  the  small  species  of  Eurytellina  in 
almost  all  features  except  the  oblique  sculpture.  It  is  remarkably 
similar  to  T.  (E.)  gonida.  The  right  anterior  lateral  is  long  and 
slender  like  in  the  species  of  Eurytellina;  the  right  posterior  lateral  is 
small,  but  distinct.  The  nymph  is  short  and  thick.  Specimens  from 
the  Cercado  formation  of  the  Dominican  Republic  have  a  thinner  shell 
and  more  slender  nymph. 


174 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Other  localities. — Cercado  formation  (lower  Miocene),  Dominican 
Republic. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135707). 

Subgenus  ELLIPTOTELLINA,  Cossmann. 

Crossmann,  1886  .Catalogue  Illustre  des  Coquilles  Fossiles  de  l’Eocene  des 
Environs  de  Paris,  part  1,  p.  58. 

Type  (by  original  designation). — Donax  tellinella  Lamarck. 
Eocene,  Paris  Basin. 

The  following  is  a  description  of  the  subgenus  Elliptotellina: 

Shell  small,  elongate-elliptical,  moderately  inequilateral,  posterior  end 
not  distinctly  rostrate,  both  ends  rounded;  sculpture  consisting  of  fine  con¬ 
centric  rugae;  right  laterals  prominent,  posterior  one  closer  to  cardinals 
and  shorter  than  anterior  one;  left  laterals  less  distinct;  nymph  short, 
heavy;  pallial  sinus  free,  moderately  deep,  slightly  ascending,  its  apex 
U-shaped. 

The  free,  slightly  ascending  pallial  sinus  separates  Elliptotellina 
from  the  subgenus  Tellina  s.  s.  The  short,  heavy  nymph,  the  hinge, 
and  the  free  slightly  ascending  sinus  suggest  that  T.  cymobia  is  an 
Elliptotellina,  although  it  has  distinct  radial  sculpture.  At  first 
glance  this  species  looks  like  a  small  Psammobia- like  shell,  such  as 
Asaphis,  but  its  laterals  and  free  sinus  exclude  it  from  the  family 
Psammobiidae. 

The  geologic  history  of  Elliptotellina  is  discussed  under  the  follow¬ 
ing  species. 

Tellina  (Elliptotellina)  cymobia,  new  species. 

(Plate  24,  Figures  14  to  16.) 

The  following  is  a  description  of  this  species: 

Shell  small,  obscurely  wedge-shaped,  posterior  part  slightly  more  inflated 
than  anterior;  concentric  sculpture  consisting  of  distant  rugae,  radial  sculp¬ 
ture  of  posterior  part  consisting  of  distant  obscurely  beaded  ribs,  remainder 
of  shell  having  obscure  radial  striae;  right  posterior  lateral  slightly  shorter 
than  anterior;  left  laterals  distinctly  projecting  from  margin  of  shell;  pallial 
sinus  free,  slightly  ascending,  reaching  beyond  middle  of  the  shell,  its  apex 
broadly  U-shaped;  posterior  margin  of  shell  slightly  serrate,  due  to 
radial  ribs. 

Length  8  mm.;  height  4.5  mm.;  diameter  (left  valve)  2  mm. 

The  obscure  wedge-like  outline  gives  this  species  the  appearance  of 
an  elongate  Donax.  No  similar  American  Tertiary  species  has  been 
described.  In  Europe  Elliptotellina  is  confined  to  Eocene  deposits. 
T.  cymobia  may  belong  to  a  different  group,  but  it  has  the  essential 
features  of  the  type  species.  In  general  features  it  resembles  T .  ( E .) 
americana  Dali,  a  living  species  from  the  middle  Atlantic  coast  of  the 
United  States,  but  has  stronger  radial  sculpture.  It  is  much  more 
similar  to  the  living  Pacific  coast  (Panama  Bay  to  the  Galapagos 


PELECYPODS. 


175 


Islands)  species  T.  pacifica  Dali,  differing  principally  in  details  of 
sculpture.  These  two  species  are  the  only  living  American  species. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352850). 

Genus  STRIGILLA  Turton. 

Section  STRIGILLA  s.  s. 

Turton,  1822,  Conchylia  Insularum  Britannicamm,  p.  117. 

Type  (by  subsequent  designation,  Gray,  1847). — Tellina  carnaria 
Linne.  Recent,  Hatteras  southward  to  Brazil. 

The  following  is  a  description  of  the  section  Strigilla  s.  s. : 

Shell  medium-sized,  ovate-trigonal;  sculpture  consisting  of  divaricating 
rugae;  on  the  anterior  part  of  the  shell  they  are  bent  upward,  then  down¬ 
ward,  these  rugae  are  replaced  in  the  central  part  of  the  shell  by  very 
oblique,  more  closely  spaced  rugae,  meeting  at  an  acute  angle  oblique  rugae 
on  the  posterior  end;  hinge  of  right  valve  consisting  of  a  slender  anterior 
cardinal  (3a),  a  heavier  bifid  posterior  cardinal  (36),  and  heavy  anterior 
and  posterior  laterals,  the  posterior  one  farther  from  the  cardinals;  hinge 
of  left  valve  consisting  of  a  slender  bifid  anterior  cardinal  (2),  a  slender 
posterior  cardinal  (4)  and  relatively  strong  anterior  and  posterior  laterals; 
pallial  sinus  wholly  confluent  with  pallial  line,  uniting  adductor  scars  by 
a  wavy  line  convex  downward  near  anterior  end  and  convex  upward  near 
posterior  end. 

The  living  species  of  Strigilla  are  confined  to  tropical  and  sub¬ 
tropical  West  Indian,  West  African  and  Pacific  waters. 

Strigilla  (Strigilla)  pisiformis  (Linne). 

(Plate  24,  Figures  17,  18.) 

Tellina  pisiformis  Linne,  1758,  Syst.  Nat.,  ed.  10,  p.  677.  Hanley,  1847,  Thes. 
Conch.,  Tellina,  p.  261,  plate  51,  fig.  30. 

Cardium  discors  Montagu,  1803,  Test.  Brit.,  p.  84. 

Strigilla  pisiformis  (Linne),  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol. 
15,  p.  249.  Dali,  1900,  Proc.  U.  S.  Nat.  Mus.,  vol.  23,  p.  298.  Dali,  1900, 
Trans.  Wagner  Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  5,  pp.  1038-1039. 
Dali  and  Simpson,  1901,  Bull.  U.  S.  Fish  Comm.,  vol.  20,  part  1,  p.  482. 
Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5,  p.  389,  plate  65,  fig.  6. 
Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  73,  p.  426.  Olsson, 
1922,  Bull.  Amer.  Paleontology,  vol.  9,  pp.  426-427. 

The  following  is  a  description  of  Bowden  specimens  of  this  species : 

Shell  small,  trigonal-ovate,  strongly  inflated,  inequilateral;  umbos  full, 
broad,  high,  placed  nearer  anterior  end;  sculpture  consisting  of  oblique 
rugae  that  are  slightly  bent  upward  at  anterior  end,  and  near  posterior 
end  meet  at  an  angle  more  obscure  oblique  rugae;  left  posterior  cardinal 
(4)  very  slender;  anterior  laterals  closer  to  the  cardinals  than  posterior. 

Length  7.5  mm.;  height  6.5  mm.;  diameter  (right  valve)  2.5  mm. 

On  some  valves  the  closely  spaced  rugae  at  the  posterior  end  are 
angulated  before  meeting  the  coarser  rugae  that  sculpture  the  central 
part  of  the  shell.  Young  shells  are  more  orbicular  than  adults.  The 
largest  valve  has  the  following  dimensions:  length  9.5  mm.;  height 
8.5  mm. ;  diameter  2.7  mm. 


176 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Bowden  specimens  run  a  little  smaller  than  Recent  ones,  and  are  a 
little  more  inequilateral,  and  have  higher  and  fuller  umbos. 

Other  localities. — Cercado  formation  (lower  Miocene),  Dominican 
Republic.  Gatun  formation  (middle  Miocene),  Costa  Rica.  Living, 
Hatteras  southward  through  the  West  Indies. 

Genus  MACOMA  Leach. 

Subgenus  MACOMA  s.  s. 

Leach,  1819,  in  John  Ross,  A  voyage  of  discovery  made  under  the  orders  oT 
the  Admiralty  in  His  Majesty’s  ships  Isabella  and  Alexander  for  the 
purpose  of  exploring  Bafiins  Bay  and  inquiring  into  the  probability  of 
a  north-west  passage,  Appendix  n,  p.  lxii. 

Type  ( by  monotypy) . — Macoma  tenera  Leach  ( =  Tellina  calcarea 
Gmelin).  Recent,  northern  seas  of  Europe  and  North  America. 

The  following  is  a  description  of  the  subgenus  Macoma  s.  s.: 

Shell  medium-sized,  elongate-ovate,  inequilateral;  sculpture  consisting  of 
incremental ;  hinge  of  right  valve  consisting  of  a  slender  anterior  cardinal 
(3a)  and  a  widely  and  deeply  bifid  posterior  cardinal  (36) ;  hinge  of  left 
valve  consisting  of  a  widely  and  deeply  bifid  anterior  cardinal  (2)  and  a 
slender  posterior  cardinal  (4) ;  pallial  sinus  deep,  confluent  with  pallial 
line  along  about  half  its  length,  its  apex  U-shaped. 

There  are  no  Bowden  species  of  Macoma  s.  s.,  which  live  in  boreal 
and  temperate  seas. 

Subgenus  PSAMMACOMA  Dali. 

Section  PSAMMACOMA  s.  s. 

Dali,  1900,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  292. 

Type  {by  original  designation). — Tellina  Candida  Lamarck.  Recent, 
Indo-Paeific. 

The  following  is  a  description  of  the  section  Psammacoma: 

Shell  medium-sized,  elongate-ovate,  inequilateral;  sculpture  consisting 
of  incrementals ;  hinge  resembling  Macoma  s.  s. ;  pallial  sinus  moderately 
deep,  confluent  with  pallial  line  along  about  half  its  length,  its  apex  broadly 
U-shaped. 

Psammacoma,  which  lives  in  the  tropical  seas,  is  more  elongate  than 
Macoma  s.  s.,  and  the  lower  limb  of  its  pallial  sinus  rises  more  steeply. 
The  earliest  species  is  recorded  from  lower  Miocene  deposits. 

Key  to  the  Bowden  species  of  Psammacoma  s.  s. 

Shell  very  elongate,  posterior  end  conspiciously  extended .  M.  ( P .)  tracta 

Shell  moderately  elongate,  posterior  end  not  conspicuously  extended..  M.  (P.)  olivella 

Macoma  (Psammacoma)  tracta  Dali. 

(Plate  24,  Figure  19.) 

Macoma  ( Psammacoma )  tracta  Dali,  1900  (part),  Trans.  Wagner  Free  Inst. 
Sci.  Philadelphia,  vol.  3,  part  5,  p.  1053,  plate  47,  fig.  13. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  thin,  rather  compressed,  elongated,  inequilateral,  the  anterior 
end  longer;  beaks  low,  not  conspicuous;  posterior  end  slightly  flexed  to  the 


PELECYPODS. 


177 


right;  anterior  end  higher,  rounded,  posterior  attenuated,  bluntly  termi¬ 
nated;  surface  smooth,  except  for  faint  incremental  lines;  interior  (inac¬ 
cessible  in  the  specimens).  Lon.  12.7,  alt.  5,  diam.  2  mm. 

Type  locality. — Bowden,  Jamaica. 

This  species  is  represented  by  the  holotype,  a  small  right  valve,  and 
a  larger  left  valve  that  has  the  following  dimensions:  length  22  mm.; 
height  10  mm.;  diameter  about  2.5  mm.  It  is  more  elongate  than 
the  other  Bowden  species,  M.  olivella  Dali,  and  its  posterior  end  is 
more  extended.  It  resembles  M.  yaquensis  Maury,  a  species  from 
the  Cercado  formation  of  the  Dominican  Republic,  but  is  more 
elongate  and  more  inequilateral. 

Specimens  from  the  Chipola  formation  of  Florida,  referred  to  M. 
tracta,  are  no  longer  in  the  U.  S.  National  Museum.  Broken  speci¬ 
mens  from  the  Shoal  River  formation  labeled  M.  tracta  represent  a 
new  species  described  by  Gardner  (Ms.). 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135702). 

Macoma  (Psammacoma)  olivella  Dali. 

(Plate  24,  Figures  20,  21.) 

Macoma  ( Psammacoma )  olivella  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci. 

Philadelphia,  vol.  3,  part  5,  p.  1054,  plate  47,  fig.  20. 

The  following  is  the  original  description  of  this  species : 

Shell  large,  solid,  moderately  convex,  with  rather  full,  conspicuous  beaks, 
equivalve,  very  inequilateral;  anterior  dorsal  slope  rectilinear,  anterior  end 
rounded;  posterior  dorsal  slope  slightly  concave,  posterior  end  much 
shorter,  rounded  below,  blunt  terminally  and  subangulate  at  its  junction 
with  the  dorsal  line ;  an  elongated  lunule  and  escutcheon,  moderately 
impressed  and  not  very  definitely  limited,  are  present;  surface  smooth, 
except  for  lines  of  growth  and  on  the  ridge  bounding  the  lunule,  which  is 
slightly  undulated,  especially  near  the  beaks;  hinge  normal,  teeth  rather 
small,  pallial  sinus  gibbous,  short,  partly  free  below.  Lon.  23,  alt.  13, 
diam.  5  mm. 

Type  locality. — Bowden,  Jamaica. 

This  species  is  known  only  from  the  holotype,  a  broken  right  valve. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135708). 

Subgenus  CYMATOICA  Dali. 

Dali,  1900,  Proceedings  U.  S.  Nat.  Mus.,  vol.  23,  p.  292 

Type  (by  original  designation) . — Tellina  undulata  Hanley.  Recent, 
Pacific  coast  of  Central  America. 

The  following  is  a  description  of  the  subgenus  Cymatoica: 

Shell  small,  thin,  elongate,  ovate,  posterior  end  rostrate;  sculpture  con¬ 
sisting  of  coarse,  concentric  or  slightly  oblique  waves;  hinge  resembling 
Macoma  s.  s.,  the  right  anterior  cardinal  (3a)  relatively  heavy;  pallial  sinus 
moderately  deep,  U-shaped,  confluent  with  pallial  line  along  less  than  half 
its  length. 


178 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Cymatoica,  characterized  by  its  small,  thin  rostrate  shell,  and  coarse 
sculpture,  is  a  tropical  American  group  represented  by  living  species 
in  the  West  Indies  and  on  the  Pacific  coast  of  Central  America.  The 
earliest  species  is  of  lower  Miocene  age. 

Macoma  (Cymatoica)  vendryesi  Dali. 

(Plate  24,  Figures  22  to  24.) 

Macoma  ( Cymatoica )  vendryesi  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  5,  p.  1056,  plate  46,  fig.  3. 

The  following  is  the  original  description  of  this  species: 

Shell  minute,  thin,  flexuous,  rostrate,  inequivalve,  inequilateral,  gaping 
behind,  moderately  inflated,  anterior  end  full,  rounded,  shorter;  posterior 
end  longer,  rectilinear  above,  sinuous  below,  produced  into  an  obliquely 
truncated  rostrum;  beaks  low,  pustular;  left  valve  slightly  less  convex 
than  the  right  and  a  little  longer;  surface  concentrically  irregular  undulated 
except  on  the  posterior  dorsal  area,  which  is  transversely  striated;  pallial 
sinus  small,  short,  partly  confluent  below  with  the  pallial  line.  Lon.  7, 
alt.  4,  diam.  2  mm. 

Type  locality. — Bowden,  Jamaica. 

M.  (C.)  hispaniolae  Maury,  from  the  Cercado  formation  of  the 
Dominican  Republic  is  very  similar,  but  is  slightly  larger  and  more 
elongate. 

Type  material. — 2  cotypes  (left  valves,  U.S.  Nat.  Mus.  No.  135695). 

Family  SEMELIDAE. 

Genus  SEMELE  Schumacher. 

Section  SEMELE  s.  s. 

Schumacher,  1817,  Essai  d’un  Nouveau  Systeme  des  Habitations  des  Vers 
Testaces,  p.  165. 

Type  (by  monotypy). — Tellina  reticulata  Spengler.  ( =Tellina 
proficua  Pulteney).  Recent,  southeastern  United  States  and  the  West 
Indies. 

The  following  is  a  description  of  the  section  Semele  s.  s. : 

Shell  medium-sized,  elliptical-orbicular,  sculpture  consisting  of  concen¬ 
tric  lamellae  frilled  by  fine  radials;  ligament  very  narrow,  resilium  seated 
on  a  wide,  deeply  inset  chondrophore ;  hinge  of  right  valve  consisting  of  2 
slender  cardinals  (3a,  3b),  the  posterior  one  (3b)  larger,  and  strong  anterior 
and  posterior  laterals;  hinge  of  left  valve  consisting  of  2  slender  cardinals 
(2a,  2b),  the  anterior  one  (2a)  larger,  and  heavy  anterior  and  posterior 
laterals;  pallial  sinus  ascending,  reaching  middle  of  shell,  its  apex  broadly 
U-shaped,  entirely  free  of  pallial  line. 

The  living  species  of  Semele,  like  the  Tertiary  species,  are  widely 
distributed  in  the  tropical  and  subtropical  seas. 

Semele  (Semele)  calliconcinnata,  new  species. 

(Plate  25,  Figures  1,  2.) 

The  following  is  a  description  of  this  species : 

Shell  small,  subelliptical,  moderately  inequilateral,  moderately  inflated; 
sculpture  reticulate,  consisting  of  equally  spaced  concentric  lamellae,  their 


PELECYPODS. 


179 


edges  thickened  and  frilled  at  the  points  of  intersection  with  narrow  radial 
threads,  which  are  separated  by  slightly  wider  interspaces  and  are  more 
closely  spaced  on  median  part  of  shell;  near  the  ends  conspicuous  beads 
lie  at  the  intersections ;  between  the  concentric  lamellae  are  fine  concentric 
threads;  left  laterals  weak;  pallial  sinus  deep,  its  apex  broadly  U-shaped. 

Length  9  mm.;  height  6.5  mm.;  diameter  (left  valve)  1.8  mm. 

This  species  closely  resembles  young  specimens  of  the  Pliocene  and 
living  species  S.  bellastriata  (Conrad),  but  is  more  inflated,  and  has 
more  broadly  rounded  ends  and  fewer  and  wider  radial  threads. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352853). 


Genus  ABRA  Lamarck. 

Section  ABRA  s.  s. 

Leach  (manuscript  name  in)  Lamarck,  1818,  Histoire  Naturelle  des  Animaux 
sans  Vertebres,  vol.  5,  p.  492. 

Type  ( by  monotypy). — Mactra  tenuis  Montagu.  Recent,  seas  of 
Europe. 

The  following  is  a  description  of  the  section  Abra  s.  s.: 

Shell  small,  trigonal;  sculpture  consisting  of  incrementals;  ligament 
narrow,  resilium  seated  on  a  wide,  deeply  inset  chondrophore ;  hinge  of 
right  valve  consisting  of  2  cardinals  (3a,  3b),  the  posterior  one  (3b)  heavier, 
and  slender  anterior  and  posterior  laterals;  hinge  of  left  valve  consisting 
of  2  cardinals  (2a,  2b),  the  posterior  one  (2b)  very  small;  pallial  sinus  deep, 
very  wide,  confluent  with  pallial  line. 

Abra  is  represented  in  both  temperate  and  tropical  Tertiary  and 
living  faunas  of  Europe  and  America. 

Key  to  the  Bowden  species  of  Abra  s.  s. 


Sculpture  consisting  of  incrementals . A.  (A.)  triangulata 

Sculpture  consisting  of  thin  concentric  threads .  A.  (A.)  deutera 


Abra  (Abra)  triangulata  Dali. 

(Plate  25,  Figures  3,  4.) 

Abra  triangulata  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia,  vol. 
3,  part  5,  p.  997,  plate  49,  fig.  4.  Olsson,  1922,  Bull.  Amer.  Paleontology, 
vol.  9,  p.  431,  plate  32,  fig.  10. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  thin,  polished,  subtrigonal,  nearly  equilateral,  wider  than 
high,  moderately  inflated;  beaks  pointed,  not  much  elevated,  the  dorsal 
margins  straight,  diverging  at  the  umbo  in  an  angle  of  somewhat  over  90° ; 
base  arcuate;  anterior  end  slightly  longer,  rounded;  posterior  end  shorter, 
more  pointed;  exterior  polished;  anterior  dorsal  margin  in  the  right  valve 
with  a  lateral  tooth  at  some  distance  from  the  hinge-plate ;  on  the  posterior 
margin  is  a  short  fold  not  elevated  to  become  a  tooth ;  the  left  valve  shows 
no  laterals.  Alt.  5.5,  lat.  5.25,  diam.  3.0  mm. 

Type  locality. — Bowden,  Jamaica. 


180 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  right  laterals  are  far  from  the  cardinals.  Specimens  from  the 
Gatun  formation  of  Bocas  Island,  described  by  Olsson,  are  larger  and 
more  elongate  than  the  holotype,  but  resemble  some  Bowden  speci¬ 
mens. 

Other  localities. — Gatun  formation  (middle  Miocene),  Panama. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135700). 

Abra  (Abra)  deutera,  new  species. 

(Plate  25,  Figures  5,  6.) 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  subtrigonal,  subequilateral,  anterior  end  slightly  more 
extended;  umbo  full,  low,  subcentral;  sculpture  consisting  of  fine,  thin, 
regularly  spaced  concentric  threads,  on  some  parts  of  the  shell  forming 
thin  lamellae,  and  fine  more  obscure,  widely  spaced  radial  markings; 
chondrophore  narrow ;  right  cardinals  heavy,  laterals  distant  from  cardinals ; 
pallial  sinus  obscure. 

Length  4  mm.;  height  3.5  mm.;  diameter  (right  valve)  1.6  mm. 

A.  deutera  is  represented  by  2  right  valves.  It  is  distinguished  from 
young  shells  of  A.  triangulata  by  its  less  acute  umbo,  greater  inflation, 
and  distinct  sculpture.  On  translucent  shells  the  radials  are  very 
obscure. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352855). 

Family  DONACIDAE. 

Genus  DONAX  Linne. 

Section  DONAX  s.  s. 

Linne,  1758,  Systema  Naturae,  ed.  10,  p.  682. 

Type  (by  subsequent  designation,  Gray,  18 47). — Donax  rugosa 
Linne.  Recent,  West  Indies. 

The  following  is  a  description  of  the  section  Donax  s.  s.: 

Shell  medium-sized,  inequilateral,  elongate  wedge-shaped,  posterior  end 
having  a  greater  diameter  than  anterior;  sculpture  consisting  of  slightly 
nodular  radial  threads  on  posterior  end,  and  obscure  radial  threads  on 
middle  of  shell;  ligament  narrow,  deeply  inset;  resilium  seated  on  a  short, 
wide,  excavated  nymph,  the  posterior  end  of  which  is  a  sharp-pointed  pro¬ 
jection  bent  backward  toward  ligament;  hinge  of  right  valve  consisting  of 
a  small  anterior  cardinal  (3a),  a  heavy,  bifid  and  roughened  posterior 
cardinal  (36),  and  conspicuous  double  anterior  and  posterior  laterals;  hinge 
of  left  valve  consisting  of  an  elongate  roughened  anterior  cardinal  (2),  a 
small  posterior  cardinal  (4),  and  a  conspicuous  posterior  lateral;  pallial 
sinus  deep,  its  apex  broadly  u-shaped,  partly  confluent  with  pallial  line; 
anterior  adductor  scar  higher,  longer  and  more  deeply  inset  than  posterior; 
inner  margin  of  valve  coarsely  fluted. 

Donax  trunculus  Linne,  the  only  species  given  by  Lamarck  in  the 
Prodrome,  usually  is  given  as  the  type  species.  Species  of  the  group 


PELECYPODS. 


181 


of  D.  rugosa  usually  are  placed  in  the  subgenus  Chion  Scopoli.  They 
are  characterized  by  strong  laterals. 

Donax  s.  s.  is  represented  by  living  species  in  the  tropical  seas  of 
the  West  Indies,  west  Africa  and  the  Pacific.  The  earliest  species  are 
recorded  from  European  Eocene  deposits. 

Donax  (Donax)  species. 

(Plate  25,  Figures  7,  8.) 

A  broken  right  valve  in  the  U.  S.  National  Museum  collection  seems 
to  represent  a  Donax  s.  s.,  as  it  has  strong  anterior  and  posterior 
laterals.  The  shell  is  elongate,  inequilateral,  and  has  obscure  radial 
sculpture;  the  chondrophore  is  very  small.  The  anterior  lateral  is 
longer  than  in  D.  rugosa  and  closer  to  the  cardinals. 

This  species  resembles  D.  chipolana  Dali,  from  the  Chipola  forma¬ 
tion  of  Florida. 


Section  PARADONAX  Cossmann. 

Cossmann,  in  Cossmann  and  Peyrot,  1910,  Conchologie  Neogenique  de  FAqui- 
taine,  vol.  1,  p.  293. 

Type  (by  original  designation) . — Donax  transversa  Deshayes.  Mio¬ 
cene,  France. 

The  following  is  a  description  of  the  section  Paradonax : 

Shell  small,  inequilateral,  elongate  wedge-shaped;  surface  smooth,  but 
obscure  radials  are  visible  under  the  polished  surface;  anterior  part  of 
ligament  on  left  valve  limited  on  side  toward  hinge  by  a  rib  that  extends 
down  on  hinge-plate;  chondrophore  much  smaller  and  less  deeply  excavated 
than  in  Donax  s.  s. ;  hinge  of  right  valve  consisting  of  a  very  slender  anterior 
cardinal  (3a),  a  heavier  posterior  cardinal  (36),  and  2  prominent  posterior 
lateral  lamellae;  hinge  of  left  valve  consisting  of  an  anterior  (2)  and 
posterior  (4)  cardinal,  almost  equal  in  size,  and  a  prominent  posterior 
lateral ;  pallial  sinus  resembling  Donax  s.  s. ;  inner  margin  of  valve  conspicu¬ 
ously  fluted. 

The  double  right  posterior  lateral  and  the  absence  of  anterior 
laterals  are  the  most  characteristic  features  of  Paradonax.  The  Bow¬ 
den  species,  D.  lennoxi,  is  more  equilateral  and  more  trigonal  than  the 
type  species;  its  nymph  is  so  small  that  it  is  obscure;  its  left  posterior 
lateral  is  closer  to  the  cardinals  than  in  the  type  species.  No  right 
valves  of  this  species  have  been  found,  but  right  valves  of  D.  aequalis 
Gabb,  a  similar  Miocene  species  from  the  Dominican  Republic,  have 
the  same  hinge  as  the  type  species.  The  rib  along  the  anterior  part 
of  the  ligament  on  left  valves  of  D.  transversa  extends  down  on  the 
hinge  plate  as  a  false  tooth.  • 

Paradonax  has  been  represented  in  European  waters  since  Eocene 
time.  D.  lennoxi  and  D.  aequalis  are  the  only  American  species  so 
far  known. 


182 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Donax  (Paradonax)  lennoxi,  new  species. 

(Plate  25,  Figures  9,  10.) 

Donax  aequalis  Dali,  1900  (part,  not  Gabb),  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  5,  p.  966. 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  trigonal,  subequilateral ;  posterior  end  more  inflated 
and  less  extended  than  anterior;  sculpture  consisting  of  narrow  radial 
threads  on  posterior  end,  and  of  obscure  radial  markings,  not  standing  in 
relief  except  on  worn  areas,  on  the  rest  of  the  shell;  chondrophore  very 
small;  rib  along  anterior  part  of  ligament  extending  down  on  hinge  plate 
of  left  valve;  hinge  of  left  valve  consisting  of  a  long,  slender  anterior 
cardinal  (2),  a  smaller  and  heavier  posterior  cardinal  (4),  and  a  posterior 
lateral;  pallial  sinus  obscure;  inner  ventral  margin  finely  fluted. 

Length  4.5  mm.;  height  3.2  mm.;  diameter  (left  valve)  1.1  mm. 

This  species  resembles  D.  aequalis  Gabb,  from  the  Cercado  forma¬ 
tion  of  the  Dominican  Republic,  but  is  smaller,  more  inequilateral, 
and  has  less  distinct  sculpture. 

Type  material. — Holotype  (left  valve,  1  of  3  specimens  in  the  Hen¬ 
derson  collection  labeled  Donax  aequalis  Gabb,  U.  S.  Nat.  Mus.  No. 
135693). 

Superfamily  SOLENACEA. 

Family  SOLENIDAE. 

Genus  PSAMOSOLEN  Risso. 

Risso,  1826,  Histoire  naturelle  des  principales  productions  de  l’Europe  meri- 
dionale  et  particulierement  de  celles  des  environs  de  Nice  et  des  Alpes 
Maritimes,  vol.  5,  p.  397,  (index).  Correction  for  Psammobia  on  p.  375, 
vol.  4. 

Type  (by  subsequent  designation,  Dali  1900). — Solen  strigilatus 
Linne.  Recent,  Mediterranean  Sea. 

The  following  is  a  description  of  the  genus  Psamosolen: 

Shell  large,  subrectangular,  both  ends  rounded,  moderately  inequilateral, 
gaping  at  both  ends;  sculpture  consisting  of  distant  oblique  rugae  that 
disappear  on  anterior  end;  nymph  long,  thick;  hinge  of  right  valve  consist¬ 
ing  of  a  long  conical  anterior  tooth  (3a)  bent  upward,  and  a  compressed 
oblique  posterior  tooth  (36) ;  hinge  of  left  valve  consisting  of  a  short 
anterior  tooth  (2),  joined  to  a  slender  tooth  extending  along  the  nymph 
(46) ;  pallial  sinus  deep,  U-shaped,  the  lower  limb  almost  confluent  with 
pallial  line. 

Living  species  of  Psamosolen,  also  known  as  Solenocurtus,  are 
widely  distributed  in  the  warmer  seas.  The  Tertiary  species  had  a 
similar  extensive  distribution. 

Psamosolen  sancti-dominici  Maury. 

(Plate  25,  Figures  11  to  14.) 

Psamosolen  vicksburg ensis  Dali,  1900  (part,  not  Aldrich),  Trans.  Wagner  Free 
Inst.  Sci.  Philadelphia,  vol.  3,  part  5,  p.  960. 

Psamosolen  sancti-dominici  Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5, 
pp.  392-393,  plate  63,  fig.  13. 


PELECYPODS. 


183 


The  following  is  the  original  description  of  this  species: 

Shell,  thin,  delicate,  with  a  broad  shallow  sulcus  passing  from  the  umbo 
to  the  ventral  margin;  dorsal  and  ventral  margins  subrectilinear,  almost 
parallel;  surface  marked  by  occasional,  concentric  growth  lines,  and  very 
elegantly  chiseled  with  close-set,  slightly  wavy,  parallel,  incised  lines  which 
run  in  an  oblique  direction  over  the  posterior  and  central  part  of  the  valve, 
but  at  the  anterior  [posterior]  end  their  distal  ends  turn  forwards  and 
upwards  in  graceful  curves;  very  near  the  anterior  dorsal  margin  the 

incised  lines  are  obsolete .  Pallial  sinus  tongue-shaped,  very  deep, 

extending  forward  into  the  anterior  third  of  the  valve.  Length  of  shell  27, 
altitude  12,  semi-diameter  4  mm. 

Type  locality. — Bluff  3,  Rio  Mao,  Dominican  Republic. 

The  largest  Bowden  specimen  has  the  following  dimensions:  length 
48  mm.;  height  19.5  mm.;  diameter  (left  valve)  6.5  mm.  The  type 
is  much  smaller,  but  broken  valves  from  the  Cercado  formation  are  a 
little  larger  than  the  largest  Bowden  valves. 

The  shell  is  very  inequilateral.  The  oblique  rugae  are  absent  on 
the  anterior  end,  and  on  large  shells  disappear  on  the  extreme  pos¬ 
terior  part.  They  are  more  closely  spaced  on  some  shells  than  on 
others. 

This  species  is  larger  than  P.  vicksburg ensis  (Aldrich),  from  the 
Byram  marl  of  Mississippi,  more  elongate,  more  inflated,  and  has  less 
abruptly  rounded  ends.  It  closely  resembles  the  Pliocene  and  living 
P.  cumingianus  (Dunker),  but  is  a  little  less  inequilateral  and  the 
central  part  of  the  shell  is  more  depressed. 

Small  specimens  from  the  Gurabo  formation  of  the  Dominican 
Republic  seem  to  represent  this  species. 

Other  localities. — Cercado  formation  (lower  Miocene),  and  Gurabo 
formation  (middle  Miocene),  Dominican  Republic. 

Type  material. — Cornell  University. 

Superfamily  MACTRACEA. 

Family  MACTRIDAE. 

Genus  SPISULA  Gray. 

Subgenus  SPISULA  s.  s. 

Section  SPISULA  s.  s. 

Gray,  1838,  Annals  and  Magazine  of  Natural  History,  new  ser.,  vol.  1,  p.  372. 

Type  (by  subsequent  designation ,  Gray,  184-7). — Mactra  solida 
Linne.  Recent,  seas  of  Europe. 

The  following  is  a  description  of  the  subgenus  Spisula  s.  s. : 

Shell  medium-sized,  trigonal-ovate,  subequilateral,  posterior  end  having 
an  obscure  ridge;  ligament  small,  seated  on  narrow  area  along  dorsal 
margin,  which  is  not  separated  from  the  chondrophore  by  a  ridge;  chondro- 
phore  large,  triangular;  hinge  of  right  valve  consisting  of  an  anterior 
cardinal  divided  into  a  long  anterior  part  (3a)  and  a  short  posterior  part 
(36),  which  is  continuous  with  the  thin  plate  along  the  side  of  the  chondro- 


184 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


phore,  and  2  anterior  and  posterior  laterals,  their  inner  faces  bearing  file-like 
ridges;  hinge  of  left  valve  consisting  of  an  anterior  cardinal  divided  to 
form  an  inverted  V  (2a,  26),  and  an  anterior  and  posterior  lateral,  their 
upper  and  lower  surfaces  ridged;  pallial  sinus  short,  U-shaped. 

The  absence  of  a  ridge  between  the  ligament  area  and  chondrophore 
is  the  most  characteristic  feature  of  the  genus  Spisula. 

Section  MACTROMERIS  Conrad. 

Conrad,  1868,  American  Journal  of  Conchology,  vol.  3,  part  3,  appendix  p.  45. 

Type  (by  subsequent  designation,  Dali,  1898). — Spisula  ovalis 
(Gould)  ( =Mactra  polynyma  Stimpson).  East  coast  of  the  United 
States. 

The  following  is  a  description  of  the  section  Mactromeris: 

Shell  large,  trigonal;  hinge  resembling  Spisula  s.  s.,  but  the  laterals  are 
not  ridged;  sinus  resembling  Spisula  s.  s. 

Mactromeris  is  an  American  group  of  Mactroids,  first  appearing  in 
the  Oak  Grove  sand  (lower  Miocene)  of  Florida. 

Spinula  (Mactromeris)  matleyi,  new  species. 

(Plate  25,  Figures  15,  16.) 

The  following  is  a  description  of  this  species: 

Shell  small,  elongate-trigonal,  subequilateral,  posterior  end  obscurely 
ridged;  sculpture  consisting  of  incrementals ;  ligament  area  separated  from 
the  large  chondrophore  by  a  very  low  ridge;  hinge  of  right  valve  consisting 
of  an  anterior  cardinal  divided  into  a  long  anterior  part  (3a)  and  a  shorter 
posterior  part  (36)  continuous  with  the  thin  ridge  along  the  anterior  side 
of  the  chondrophore;  upper  margin  of  shell  thickened  along  posterior  part 
of  cardinal;  anterior  and  posterior  laterals  short. 

Length  25  mm.;  height  16.5  mm.;  diameter  (right  valve)  4  mm. 

This  species  is  represented  by  an  imperfect  right  valve,  but  all  the 
features  of  the  shell,  except  the  pallial  sinus,  are  visible.  The  anterior 
part  (3a)  of  the  cardinal  is  broken,  but  apparently  it  is  not  continuous 
with  the  lower  anterior  lateral,  although  the  anterior  laterals  are 
closer  to  the  cardinal  than  in  the  type  species.  The  shell  is  much 
smaller  and  more  elongate  than  the  type  species,  resembling  the  genus 
Mulinia. 

S.  ( M .)  matleyi  resembles  S.  (M.)  duplinensis  Dali,  from  the  Dup¬ 
lin  marl  of  North  Carolina,  but  is  much  smaller;  its  ligament  area  is 
more  excavated;  and  the  thickened  margin  of  the  shell  is  more  dis¬ 
tinctly  joined  to  the  posterior  part  (36)  of  the  right  cardinal. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
352857). 

Family  MESODESMATIDAE. 

Genus  ERVILIA  Turton. 

Turton,  1822,  Conchylia  Insularum  Brittannicarum,  p.  55. 

Type  (by  monotypy). — My  a  nitens  Montagu.  Recent,  West  Indies. 


PELECYPODS. 


185 


The  following  is  a  description  of  the  genus  Ervilia: 

Shell  small,  elongate-ovate,  moderately  inequilateral ;  sculpture  consisting 
of  closely  spaced  concentric  rugae;  chondrophore  triangular,  placed  under 
umbo;  hinge  of  right  valve  consisting  of  a  heavy  bifid  anterior  cardinal  (3) 
and  a  rudimentary  posterior  tooth  probably  representing  a  lateral;  hinge 
of  left  valve  consisting  of  an  obscure  oblique,  inverted  V-shaped  anterior 
cardinal,  the  posterior  part  (26)  coinciding  with  edge  of  chondrophore,  the 
anterior  part  (2a)  smaller  and  scarcely  diverging  from  margin  of  shell; 
left  valve  having  an  anterior  and  posterior  thickening  of  the  hinge  margin 
close  to  the  chondrophore;  pallial  sinus  short,  broadly  U-shaped;  interior 
of  shell  thickened  between  umbo  and  anterior  adductor  scar. 

In  Europe,  Ervilia  first  appears  in  the  Aquitanian  of  Aquitaine. 
The  earliest  American  species  comes  from  the  Chipola  formation 
(lower  Miocene)  of  Florida  and  deposits  of  the  same  age  in  the  West 
Indies.  The  living  species  inhabit  the  warm  temperate  and  tropical 
seas. 

Eivilia  gabbi,  new  species. 

(Plate  25,  Figures  17,  18.) 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  ovate-trigonal,  subequilateral,  strongly  inflated;  poste¬ 
rior  end  slightly  more  extended  and  more  abruptly  rounded ;  dorsal  margins 
subequal  in  length  and  sloping  at  same  angle;  base  gently  and  symmetri¬ 
cally  arcuate;  umbos  full,  subcentral;  sculpture  consisting  of  fine  regular 
concentric  rugae,  obscure  radial  markings  are  visible  on  the  posterior  end; 
anterior  and  posterior  dorsal  margins  of  right  valve  having  long  grooves. 

Length  5  mm.;  height  3.2  mm.;  diameter  (left  valve)  1.5  mm. 

This  species  is  virtually  equilateral,  strongly  inflated,  and  has  rela¬ 
tively  conspicuous  concentric  sculpture.  Both  species  from  the 
Chipola  formation,  E.  chipolana  Dali  and  E.  triangularis  Dali,  are 
more  inequilateral,  and  have  a  more  extended  posterior  end  and  less 
conspicuous  sculpture.  E.  gabbi  more  closely  resembles  the  Duplin 
marl  species  E.  lata  Dali  and  the  living  E.  concentrica  Gould,  both  of 
which  are  slightly  more  inequilateral  and  more  compressed.  The 
Pliocene  species  E.  polita  Dali  is  slightly  larger,  more  inequilateral, 
and  more  compressed,  and  has  weaker  sculpture. 

Type  material . — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  352858). 

Superfamily  MYACEA. 

Family  CORBULIDAE. 

Genus  CORBULA  Lamarck. 

Section  CORBULA  s.  s. 

Lamarck,  1801,  Systeme  des  Animaux  sans  Vertebres,  p.  137. 

Type  {by  subsequent  designation,  Gray,  1847). — Corbula  sulcata 
Lamarck.  Recent,  west  coast  of  Africa.1 

1 1  have  not  seen  the  type  species.  The  description  is  taken  from  Cossmann  and  Peyrot, 
1909. 


186 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  following  is  a  description  of  the  section  Corbula  s.  s. : 

Shell  small,  trigonal-ovate,  inequilateral,  inequivalve,  the  right  valve 
larger,  posterior  end  rostrate;  sculpture  consisting  of  concentric  waves, 
similar  on  both  valves  of  the  type  species;  chondrophore  deeply  inset; 
hinge  of  right  valve  consisting  of  a  strong  anterior  cardinal  and  an  obscure 
posterior  lateral;  left  valve  bearing  a  deep  socket  in  front  of  the  chondro¬ 
phore,  and  an  obscure  lateral  lamella  behind  the  chondrophore ;  pallial  sinus 
very  shallow. 

Aside  from  the  peculiar  Bothro corbula,  two  kinds  of  Corbulas  are 
represented  in  the  Bowden  formation.  Neither  is  exactly  similar  to 
Corbula  sulcata.  C.  sericea  is  moderately  inequivalve  and  the  valves 
have  similar  sculpture.  C.  heterogena  is  very  inequivalve  and  the 
valves  have  dissimilar  sculpture.  American  Tertiary  species  similar 
to  C.  sericea  are  commonly  placed  in  the  section  Cuneocorbula  Coss- 
mann,  but  the  type  of  that  section — C.  biangulata  Deshayes,  an 
Eocene  species  from  the  Paris  Basin — is  bicarinate.  American  Ter¬ 
tiary  species  similar  to  C.  heterogena  usually  are  placed  in  the  section 
Aloidis  Megerle  von  Muhlfeldt,  which  has  the  same  type  as  Corbula 
s.  s.  Some  European  palaeontologists  use  the  name  Agina  Turton  for 
Corbulas  similar  to  C.  heterogena.  “Mya  purpurea  Montagu”  is  the 
only  species  listed  by  Turton  under  Agina.  According  to  Turton’s 
figure,  this  species  is  a  Saxicava.  As  no  name  seems  to  be  available 
for  Corbulas  having  dissimilarly  sculptured  valves,  both  Bowden 
species  are  placed  in  the  section  Corbula  s.  s. 

Key  to  the  Bowden  species  of  Corbula  s.  s. 

Shell  moderately  inequivalve,  sculpture  similar  on  the  two  valves - C.  (C.)  sericea 

Shell  very  inequivalve,  sculpture  dissimilar  on  the  two  valves....  C.  ( C .)  heterogena 

Corbula  (Corbula)  sericea  Dali. 

(Plate  25,  Figures  19  to  22.) 

Corbula  cubaniana  Guppy,  1874  (part,  not  d’Orbigny),  Geol.  Mag,  decade  2, 
vol.  1,  p.  441  (list). 

Corbula  ( Cuneocorbula )  sericea  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci. 
Philadelphia,  vol.  3,  part  4,  p.  848;  1900,  vol.  3,  part  5,  plate  36,  fig.  8. 

? Corbula  sericea  Dali,  Brown  and  Pilsbry,  1911,  Proc.  Acad.  Nat.  Sci.  Phila¬ 
delphia,  vol.  63,  p.  371.  Not  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.  Phila¬ 
delphia,  vol.  73,  p.  427  (=C.  cercadica  Maury). 

The  following  is  the  original  description  of  this  species: 

Shell  much  like  the  preceding  species  [C.  seminella  Dali]  in  general 
form,  but  slightly  larger  and  with  less  emargination  beneath  the  rostrum. 
The  sculpture,  however,  is  quite  different,  being  of  very  numerous,  equal, 
fine,  sharp,  close-set  ribs,  the  interspaces  crossed  by  fine,  close,  sharp  radial 
striation,  which  at  once  distinguishes  it  from  any  of  the  allied  species. 
Both  valves  are  similarly  sculptured,  the  sculpture  becoming  obsolete  on 
the  beaks.  Lon.  4.5,  alt.  3.5,  diam.  2.3  mm.  The  largest  valve  measures 
5.4  by  4  mm. 

Type  locality. — Limon,  Costa  Rica. 


PELECYPODS. 


187 


The  right  valve  of  this  species  is  slightly  larger  than  the  left.  Guppy 
listed  “C.  cubaniana”  only  from  Pliocene  beds  at  Matura,  Trinidad, 
but  specimens  of  C.  sericea  from  Bowden  in  the  Guppy  collection  are 
labeled  “C.  cubaniana  ” 

The  type  of  C.  sericea  is  from  Limon,  Costa  Rica.  Its  age  is  not 
known,  as  both  Miocene  and  Pliocene  beds  crop  out  near  Limon.  The 
specimens  from  Bowden  are  smaller  and  heavier,  and  many  have 
obscure  radial  sculpture,  but  they  resemble  small  specimens  from 
Limon. 

C.  sericea  is  very  abundant  at  Bowden.  It  is  smaller  and  not  so 
elongate  as  C.  cercadica  Maury,  from  the  Cercado  and  Gurabo  forma¬ 
tions  of  the  Dominican  Republic.  The  Pliocene  (?)  species  from 
Costa  Rica  described  by  Gabb  as  C.  lavaieana  d’Orbigny  is  even  more 
elongate.  The  Miocene  species  from  Costa  Rica  described  by  Gabb 
under  the  same  name  may  be  C.  sericea.  The  valve  from  the  Gatun 
formation  of  the  Canal  Zone,  called  C.  sericea  by  Brown  and  Pilsbry, 
is  larger,  and  has  a  wider  posterior  slope  and  straighter  posterior 
margin. 

Other  localities. — Middle  Miocene  (?),  Costa  Rica.  ?  Gatun  for¬ 
mation  (middle  Miocene),  Panama  Canal  Zone. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135655). 

Corbula  (Corbula)  heterogena  Dali. 

(Plate  26,  Figures  1  to  4.) 

Corbula  vieta  Guppy,  1866  (part),  Quart.  Jour.  Geol.  Soc.  London,  vol.  22, 
pp.  580-581  (not  plate  26,  fig.  8),  right  valve.  Guppy,  1873,  Proc.  Sci. 
Assoc.  Trinidad,  vol.  2,  No.  2,  p.  85  (name  only).  Guppy,  1874  (part), 
Geol.  Mag.,  decade  2,  vol.  1,  p.  441  (list). 

Corbula  disparilis  Guppy  and  Dali,  (not  d’Orbigny),  1896,  Proc.  U.  S.  Nat. 
Mus.,  vol.  19.  p.  327. 

Corbula  ( Aloidis )  heterogena  Guppy  Mss.,  Dali,  1898  (part),  Trans.  Wagner 
Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  p.  850,  plate  46,  fig.  15. 

Corbula  heterogena  Guppy,  Brown  and  Pilsbry,  Proc.  Acad.  Nat.  Sci.  Phila- 
deplhia,  vol.  63,  p.  372. 

The  following  is  the  original  description  of  this  species: 

This  form  is  very  close  to  C.  vieta,  but  differs  from  it  in  having  the  beaks 
narrower,  less  elevated,  and  less  prominent,  and  the  posterior  part  of  the 
shell  more  produced.  Lon.  9.5,  alt.  8,  diam.  5  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Right  valve  medium-sized,  high,  trigonal,  greatly  inflated,  moderately 
inequilateral,  posterior  end  slightly  more  extended;  dorsal  margins  subequal 
in  length,  concave;  anterior  end  rounded,  posterior  end  truncate;  umbos 
full,  high,  strongly  incurved  and  moderately  or  strongly  prosogyrate,  sub¬ 
central;  near  the  posterior  margin  lies  an  obscure  ridge,  in  front  of  it  lies 
a  stronger  broadly  rounded  ridge;  area  between  ridges  flattened  or  slightly 


188 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


depressed ;  sculpture  consisting  of  strong  concentric  rugae  of  medium  width ; 
left  valve  small,  elongate  ovate,  moderately  inflated,  moderately  inequi¬ 
lateral  ;  anterior  end  rounded,  posterior  end  truncate ;  anterior  dorsal  margin 
slightly  concave,  posterior  dorsal  margin  slightly  longer  and  straight; 
umbos  full,  moderately  high,  placed  in  front  of  middle;  posterior  ridge  low, 
obscure;  sculpture  consisting  of  obscure,  fine  concentric  rugae,  suppressed 
over  much  or  all  of  surface,  and  about  10  to  12  very  narrow  radial  threads, 
the  posterior  slope  having  no  radial  sculpture;  chondrophore  almost  hori¬ 
zontal,  its  lower  and  posterior  margins  greatly  thickened. 

A  right  valve:  length  8  mm.;  height  7mm.;  diameter  3  mm. 

A  left  valve:  length  5.5  mm.;  height  4  mm.;  diameter  2  mm. 

Right  valves  of  this  species  are  very  abundant,  but  left  valves  are 
less  abundant.  Some  right  valves  have  a  more  extended  posterior  end 
than  others. 

The  type  material  of  C.  vieta  Guppy  (U.  S.  Nat.  Mus.  No.  115650) 
comes  from  beds  of  Miocene  age  at  Manzanilla,  Trinidad.1  These 
valves  (right  valves)  are  larger  than  right  valves  of  C.  heterogena, 
and  have  wider,  higher  umbos,  less  extended  posterior  area,  and 
slightly  coarser  sculpture.  Left  valves  of  C.  vieta  from  Manzanilla, 
described  by  Guppy  as  Erycina  tensa,  are  larger,  less  inflated  and 
more  smoothly  ovate  than  left  valves  of  C.  heterogena.  Olsson 
thought  Erycina  tensa  could  not  be  the  left  valve  of  a  Corbula,  but  an 
examination  of  Guppy’s  types  removes  any  doubt. 

Spieker2  has  compared  several  similar  Corbulas  of  this  group.  Right 
valves  of  C.  bradleyi  Nelson,  from  the  Zorritos  formation  of  Peru,  are 
less  triangular  than  right  valves  of  C.  heterogena  and  have  coarser 
sculpture.  Right  valves  of  the  species  from  the  Cercado  formation 
of  the  Dominican  Republic  described  by  Maury  as  “C.  vieta”  are  less 
elongate  and  more  inflated  than  right  valves  of  C.  heterogena;  left 
valves  have  the  same  shape,  but  the  umbo  of  the  Dominican  species 
is  lower  and  the  margin  of  the  chondrophore  is  not  so  thick.  Left 
valves  of  a  species  from  the  Gurabo  formation  of  the  Dominican 
Republic  are  more  orbicular  and  have  higher  umbos  than  left  valves 
of  C.  heterogena.  Right  valves  of  “C.  vieta”  Olsson,  from  Miocene 
beds  in  Costa  Rica  and  Panama,  also  are  less  elongate  than  C.  hetero¬ 
gena. 

C.  heterogena  seems  to  be  confined  to  the  Bowden  and  Gatun  for¬ 
mations.  There  are  many  similar  species  in  the  Miocene  and  Pliocene 
deposits  of  southeastern  United  States,  such  as  C.  chipolana  Dali 
(MS.)  Gardner  from  the  Chipola  formation,  C.  waltonensis  Gardner 
(MS.)  from  the  Oak  Grove  sand,  and  C.  caloosae  Dali  from  the 

1  Specimens  from  Matura,  Trinidad  (U.  S.  Nat.  Mus.  No.  115651)  also  are  labeled  “types," 
but  Guppy  figured  a  specimen  from  Manzanilla.  The  specimens  from  Matura  are  more  trigonla 
than  those  from  Manzanilla. 

2  E.  M.  Speiker.  Johns  Hopkins  University  Studies  in  Geology,  No.  3,  pp.  170-172,  1922. 
Spieker  erroneously  states  that  I  consolidated  C.  vieta  and  C.  heterogena.  The  citations  of  C. 
vieta  in  the  synonomy  refer  to  Guppy’s  consolidation  of  Bowden  and  Trinidad  specimens  under 
the  same  name. 


PELECYPODS. 


189 


Caloosahatchee  marl  of  Florida.  C.  disparilis  d’Orbigny  is  the  living 
West  Indian  representative  of  this  group. 

Other  localities. — Gatun  formation  (middle  Miocene),  Panama 
Canal  Zone. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
107099). 


Section  BOTHROCORBULA  Gabb. 

Gabb,  1872,  Proceedings  Academy  of  Natural  Sciences  of  Philadelphia  for 
1872,  p.  274. 

Type  (by  monotypy). — Corbula  viminea  Guppy.  Miocene, 
Jamaica. 

The  following  is  a  description  of  the  section  Bothro corbula: 

Shell  moderately  large,  thick,  elongate-ovate,  moderately  inequilateral, 
posterior  end  ridged,  right  valve  slightly  larger  than  left;  sculpture  of  both 
valves  consisting  of  coarse  concentric  waves;  in  front  of  the  umbones  lies 
a  deep  lunular  depression;  hinge  resembling  Corbula  s.  s. 

The  deep  lunular  depression  is  a  characteristic  feature  of  Bothro - 
corbula.  This  section  is  an  American  group  and  is  particularly  char¬ 
acteristic  of  the  Miocene  deposits  of  the  West  Indies  and  Central 
America,  but  occurs  in  the  subtropical  faunas  of  the  mainland.  A 
species  from  the  Chipola  formation  of  Florida,  C.  synarmostes  Dali, 
has  a  shallow  pit;  C.  radiatula  Dali,  from  the  Oak  Grove  sand  of 
Florida,  has  a  larger  and  deeper  pit;  and  C.  willcoxi  Dali,  from  the 
Caloosahatchee  marl  of  Florida,  has  as  large  and  as  deep  a  pit  as  the 
type  species.  According  to  Dali,  Stimpson  reported  having  dredged  a 
living  Bothrocorbula  in  the  deep  water  of  Florida  Strait.  The  speci¬ 
mens  were  lost  in  the  Chicago  fire.  Aside  from  this  doubtful  record, 
Bothrocorbula  is  extinct. 

Coibula  (Bothrocorbula)  viminea  Guppy. 

(Plate  26,  Figures  5  to  8.) 

Corbula  viminea  Guppy,  1866,  Quart.  Journ.  Geol.  Soc.  London,  vol.  22,  p.  293, 
plate  18,  fig.  11.  Guppy,  Geol.  Mag.,  1874,  decade  2,  vol.  1,  p.  441  (list). 
Guppy,  1876,  Quart.  Jour.  Geol.  Soc.  London,  vol.  32,  p.  529.  Not  Brown 
and  Pilsbry,  1911,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  63,  p.  372 
(=(7.  hexacyma  Brown  and  Pilsbry). 

Bothrocorbula  viminea  (Guppy),  Gabb,  1872,  Proc.  Acad.  Nat.  Sci.  Phila¬ 
delphia,  p.  274,  plate  10,  figs.  3,  3a.  Gabb,  1873,  Trans.  Amer.  Philos. 
Soc.,  n.  s.,  vol.  15,  p.  247. 

Corbula  ( Bothrocorbula )  viminea  Guppy,  Dali,  1898  (part),  Trans.  Wagner 
Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  p.  850.  Maury,  1917,  Bull. 
Amer.  Paleontology,  vol.  5,  pp.  397-398,  plate  65,  figs.  20,  21.  Pilsbry, 
1922,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  73,  p.  428.  Olsson,  1922, 
Bull.  Amer.  Paleontology,  vol.  9,  p.  442,  plate  31,  fig.  25. 

The  following  is  the  original  description  of  this  species: 

Shell  thick,  transversely  oblong,  rounded  anteriorly,  produced  posteriorly 
into  an  acute  beak;  valves  ornamented  with  stout,  rather  round,  concentric 


190 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


ribs;  hinge  with  a  single  prominent  tooth  and  a  deep  orbicular  pit  in 
front  of  it. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  large,  thick,  moderately  inflated,  elongate,  inequilateral;  posterior 
end  ridged,  base  emarginate  in  front  of  ridge;  lunular  depression  deep, 
subspherical,  larger  on  left  valve;  sculpture  consisting  of  coarse  concentric 
waves,  which  are  suppressed  before  the  posterior  ridge  is  reached,  fine 
concentric  striae  are  engraved  on  the  waves  and  are  continuous  across  the 
posterior  slope  and  the  area  in  front  of  it;  radial  sculpture  consisting  of 
fine,  obscure,  distant  radial  threads  between  the  waves,  absent  on  the 
posterior  slope. 

Length  17.5  mm.;  height  12  mm.;  diameter  (right  valve)  4.8. 

This  species  has  a  remarkably  deep  lunular  pit.  On  some  specimens 
the  faint  radial  sculpture  is  absent.  Most  of  the  specimens  from  the 
Cercado  formation  of  the  Dominican  Republic  are  smaller  and  a  little 
more  elongate  than  specimens  from  Bowden.  A  more  elongate  unde¬ 
scribed  species  occurs  in  the  Thomonde  formation  (lower  Miocene) 
of  the  Republic  of  Haiti.  No  Bothrocorbula  has  been  collected  from 
the  Gurabo  formation.  A  specimen  from  the  Gatun  formation  of  the 
Canal  Zone  in  the  collection  of  the  U.  S.  National  Museum  labeled 
C.  viminea  is  C.  hexacyma  Brown  and  Pilsbry,  a  species  remarkably 
similar  to  C.  viminea,  but  having  no  lunular  pit.  Olsson  has  reported 
C.  viminea  from  the  Gatun  formation  of  Costa  Rica. 

Other  localities. — Cercado  formation  (lower  Miocene),  Dominican 
Republic.  Gatun  formation  (middle  Miocene),  Costa  Rica. 

Type  material. — Holotype,  British  Museum  (Natural  History), 
Geological  Department,  No.  64088. 

Superfamily  PANOPEACEA. 

Family  BASTEROTIDAE. 

Genus  BASTEROTIA  Mayer. 

Section  BASTEROTIA  s.  s. 

Mayer,  in  Homes,  1870,  Abhandlungen  der  Kaiserlich-Koniglichen  Geologi* 
schen  Reichsanstalt,  vol.  4,  p.  40. 

Type  {by  monotypy). — Basterotia  corbuloides  Mayer.  Miocene, 
Vienna  basin.1 

The  following  is  a  description  of  the  section  Basterotia  s.  s. : 

Shell  medium-sized,  subquadrate,  strongly  inflated,  posterior  end  strongly 
ridged;  umbos  high,  wide,  posterior  ridge  extending  to  tip  of  umbo;  sculp¬ 
ture  consisting  of  fine  granules  and  incrementals ;  ligament  external,  seated 
on  a  tooth-like  nymph  above  and  behind  the  tooth;  hinge  of  right  valve 
consisting  of  a  prominent  subumbonal  tooth,  separated  from  nymph  by 
a  narrow  gap;  hinge  of  left  valve  consisting  of  a  similar  tooth,  separated 
from  nymph  by  socket  into  which  tooth  of  right  valve  fits;  pallial  line 
simple. 

1 1  have  not  seen  the  type  species.  The  description  is  taken  from  Cossmann  and  Peyrot. 
1909. 


PELECYPODS. 


191 


Basterotia  s.  s.  is  represented  by  Miocene  species  in  Europe.  The 
Bowden  species,  B.  bowdeniana,  is  the  only  American  Tertiary  species. 
The  living  species  seem  to  be  confined  to  the  West  Indies  and  Pacific 
Ocean. 

Basterotia  (Basterotia)  bowdeniana  (Dali). 

(Plate  26,  Figures  9,  10.) 

Anisodonta  ( Basterotia )  bowdeniana  Dali,  1900,  Trans.  Wagner  Free  Inst. 
Sci.  Philadelphia,  vol.  3,  part  5,  p.  1133. 

The  following  is  the  original  description  of  this  species: 

A  species  of  Basterotia,  which  appears  to  be  clearly  distinct  from  B.  quad - 
rata  Hinds,  is  represented  by  a  broken  right  valve  in  the  collection  made  by 
Henderson  and  Simpson  at  Bowden.  Hardly  complete  enough  to  figure, 
it  may  be  described  as  distinguished  from  B.  quadrata  by  the  following 
characters.  The  keel,  which  is  so  prominent  a  feature  in  B.  quadrata,  in 
the  present  shell  is  well  marked  only  on  the  beak,  rapidly  becoming  obso¬ 
lete  distally  and  represented  only  by  a  rounded  ridge,  which  passes 
imperceptibly  into  the  general  convexity  of  the  valve.  The  beaks  in 
B.  bowdeniana  are  less  angular  and  elevated,  the  shell  thinner  and  more 
ovate,  the  hinge-line  longer,  the  elevated  tooth  smaller  in  proportion  to 
the  shell  and  much  more  delicate.  The  sculpture  is  minutely  sagrinate, 
the  length  10.5,  the  diameter  about  5  millimeters. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  medium-sized,  subovate,  posterior  end  not  ridged,  except  near  umbo, 
where  the  ridge  is  broad  and  rounded;  umbo  low;  sculpture  consisting  of 
very  minute  granules,  absent  on  posterior  third  of  shell;  nymph  eroded, 
short,  slender,  limited  above  by  a  narrow  groove,  separated  from  the  tooth 
by  a  narrow  gap;  tooth  of  right  valve  long,  slender;  left  valve  not  known. 

In  outline  this  species  is  entirely  different  from  the  type  species 
and  the  similar  West  Indian  species  B.  granatina  Dali,  and  Pacific 
species  B.  quadrata  (Hinds).  B.  bowdeniana  closely  resembles  the 
living  West  Indian  species  known  as  B.  elliptica  (Recluz),  but  has  a 
shorter  nymph.  The  Bowden  species  apparently  resembles  B.  biali 
Cossmann  and  Peyrot,  from  the  upper  Burdigalian  of  Bordelais.  The 
outline  of  the  Bowden  species  recalls  Fulcrella,  but  the  nymph  is 
shorter,  and  the  tooth  more  slender  and  longer. 

Type  material. — Holotype  (right  valve,  U.  S.  Nat.  Mus.  No. 
135749). 

Superfamily  EDENTULACEA. 

Family  GASTROCHAENIDAE. 

Genus  GASTROCHAENA  Spengler. 

Subgenus  GASTROCHAENA  s.  s. 

Spengler,  1783,  Nye  Samling  af  det  Kongelige  Danske  Videnskabers  Selskabs 
Skrifter,  vol.  2,  p.  179. 

Type  {by  subsequent  designation,  Bucquoy,  Dautzenberg,  and  Doll - 
jus,  1896). — Gastrochaena  cuneijormis  Spengler  (?  =Mya  hians  Gme- 
lin).  Recent,  West  Indies. 


192 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  following  is  a  description  of  the  subgenus  Gastrochaena  s.  s.: 

Shell  medium-sized,  twisted,  elongate  wedge-shaped,  equivalve,  umbos 
near  anterior  end;  gape  very  wide  and  long;  sculpture  consisting  of  incre- 
mentals ;  ligament  seated  on  a  slender  nymph ;  hinge  having  no  teeth ;  under 
the  umbo  lies  a  rude  myophore;  pallial  sinus  moderately  deep,  U-shaped; 
shell  embedded  in  burrows  lined  with  calcareous  material,  or  protected  by 
a  calcareous  tube. 

In  America,  species  of  Gastrochaena  probably  first  appear  in  lower 
Miocene  deposits,  although  some  Eocene  species  are  referred  to  this 
genus.  The  living  species  are  widely  distributed. 

Gastrochaena  (Gastrochaena)  rotunda  Dali. 

(Plate  26,  Figures  11,  12.) 

Gastrochaena  ovata  Sowerby  var.  rotunda  Dali,  1898  (part),  Trans.  Wagner 
Free  Inst.  Sci.  Philadelphia,  vol.  3,  part  4,  p.  825. 

Gastrochaena  rotunda  Dali,  Olsson,  1922,  Bull.  Amer.  Paleontology,  vol.  9,  p. 
438.  Not  Dali,  1915,  Bull.  U.  S.  Nat.  Mus.  No.  90,  p.  157.  (Plate  19,  fig. 
2,  represents  a  specimen  from  the  Chipola  formation). 

The  following  is  the  original  description  of  this  species: 

Shell  resembling  the  ovata  of  the  same  size,  but  not  attaining  so  large 
a  size  as  the  adult  ovata,  with  a  more  rounded  posterior  end,  rather  shorter 
gape,  the  myophore  decidedly  larger,  wider,  and  more  conspicuous.  Lon.  7, 
lat.  3.5,  diam.  2.8  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  medium-sized,  thin,  elongate,  wedge-shaped,  umbos  near  anterior 
end;  gape  very  wide  and  long;  sculpture  consisting  of  incrementals,  which 
are  elevated  into  rude  lamellae  on  anterior  part  of  shell;  nymph  long  and 
slender;  under  the  umbo  lies  a  short  oblique  myophore;  pallial  sinus 
obscure. 

Length  19  mm.;  height  7.5  mm.;  diameter  (left  valve)  3.5  mm. 

The  left  valve  figured  is  much  larger  than  the  cotypes  and  is  corre¬ 
spondingly  larger  than  any  specimens  from  the  Chipola  formation. 
It  also  has  a  much  heavier  and  more  oblique  myophore  than  speci¬ 
mens  from  the  Chipola  formation,  which  probably  represent  a  differ¬ 
ent  species.  The  Bowden  species  resembles  the  living  G.  ovata 
Sowerby,  but  is  smaller,  thinner,  more  elongate  and  has  a  more  dis¬ 
tinct  myophore. 

A  small  similar  Gastrochaena  has  been  collected  from  the  Gurabo 
formation.  Olsson  records  G.  ovata  from  the  Gatun  formation  of 
Costa  Rica.  The  shell  figured  by  Dali  in  the  report  on  the  Tampa 
mollusks  is  from  the  Chipola  formation.  Indeterminable  burrows  are 
the  only  specimens  from  the  Tampa  formation. 

Other  localities. — Gatun  formation  (middle  Miocene),  Costa  Rica. 

Type  material. — 2  cotypes  (U.  S.  Nat.  Mus.  No.  135742). 


PELECYPODS. 


193 


Superfamily  ADESMACEA. 

Family  PHOLADIDAE. 

Genus  JOUANNETIA  Des  Moulins. 

Des  Moulins,  1828,  Bulletin  d’Histoire  Naturelle  de  la  Societe  Linneenne  de 
Bordeaux,  vol.  2,  (p.  246  of  reprint,  1845). 

Type  (by  monotypy). — Jouannetia  semicaudata  Des  Moulins. 
Miocene,  France.1 

The  following  is  a  description  of  the  genus  Jouannetia : 

Shell  thin,  strongly  inflated,  gape  closed  by  a  callus  extending  from  left 
valve  to  right;  right  valve  having  a  posterior  rostiform  appendage;  umbos 
central;  valves  having  an  oblique  groove  extending  down  from  umbos; 
sculpture  consisting  of  lamellar  incrementals,  which  are  stronger  in  front  of 
groove;  myophore  short,  slender;  pallial  sinus  deep. 

The  following  species  seem  to  be  a  Jouannetia.  At  the  present  time 
the  genus  is  confined  to  the  Indo-Pacific  region.  Eocene,  Oligocene, 
and  Miocene  species  are  recorded  from  Europe. 

Jouannetia  sphaeroidalis  (Guppy)  (MS.  name). 

(Plate  26,  Figures  13  to  15.) 

Martesia  sphaeroidalis  Guppy,  name  on  label. 

Teredina  ?  doubtful  species,  Guppy  and  Dali,  1896,  Proc.  U.  S.  Nat.  Mus., 
vol.  19,  pp.  327-328. 

The  following  is  the  description  of  this  species  given  by  Guppy  and 
Dali: 

Almost  globular,  anterior  end  finely  closely  laminose,  posterior  area 
subequal,  nearly  smooth,  the  medial  groove  feebly  marked;  callum  appar¬ 
ently  complete,  siphonal  end  slightly  gaping,  truncate,  the  margins  thick¬ 
ened  and  reflected,  the  dorsal  plates  wanting,  probably  lost.  Alt.  6  mm. 

Type  locality. — Jamaica. 

The  following  is  a  description  of  this  species: 

Shell  small,  thin,  spherical,  equivalve,  posterior  end  gaping;  posterior 
margin  of  valve  thickened,  especially  near  umbo;  umbo  low,  partly  covered 
by  callus  extending  over  anterior  part  of  shell,  closing  anterior  gape;  shell 
having  an  oblique  groove  extending  from  umbo  to  ventral  margin;  area 
between  groove  and  anterior  callus  sculptured  with  oblique  lamellar  incre¬ 
mentals;  at  the  groove  the  incrementals  are  angulated,  behind  the  groove 
they  are  non-lamellar;  interior  inaccessable. 

Length  6.5  mm.;  height  6.7  mm.;  diameter  (both  valves)  6  mm. 

This  species  is  represented  by  2  specimens  having  both  valves 
attached.  If  it  is  a  Jouannetia  both  specimens  are  not  full  grown,  as 
there  is  no  trace  of  a  posterior  appendage  on  the  right  valve.  The 
shells  are  equivalve,  a  feature  that  supports  the  supposition  that  they 
are  not  full  grown.  No  American  species  of  Jouannetia  have  hereto¬ 
fore  been  described. 


1 1  have  not  seen  the  type  species.  The  description  is  taken  from  Cossmann  and  Peyrot,  1909. 


194 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Type  material. — Holotype  (right  and  left  valves  of  the  same  shell, 
originally  in  attached  position,  U.  S.  Nat.  Mus.  No.  107100). 

Genus  M  ARTE SI  A  Leach. 

Leach,  in  Blainville,  1824,  Manuel  de  Malacologie  et  de  Conchyliogie,  p.  632. 

Type  (by  subsequent  designation,  Gray,  1847), — Pholas  clavata 
Lamarck  (=Pholas  striata  Linne).  Recent,  seas  of  Europe. 

The  following  is  a  description  of  the  genus  Martesia: 

Shell  thin,  medium-sized,  elongate,  wedge-shaped,  inequilateral,  gaping 
at  posterior  end;  a  shallow  groove  extends  from  the  umbo  to  the  ventral 
margin ;  lower  anterior  part  of  shell  covered  with  callus  closing  the  anterior 
gape,  the  edge  of  the  callus  extending  along  the  upper  anterior  margin; 
part  of  shell  in  front  of  groove  sculptured  with  roughened  threads;  back 
of  the  groove  these  threads  are  replaced  by  crude  incrementals ;  umbo 
covered  with  accessory  plates;  ventral  margins  connected  by  an  accessory 
plate  for  greater  part  of  distance  behind  groove;  myophore  long,  slender, 
curved. 

According  to  Cossmann,  Mesozoic  and  even  Carboniferous  mollusks 
have  been  referred  to  Martesia,  but  the  pre-Eocene  species  are  doubt¬ 
ful.  The  living  species  have  an  extensive  distribution. 

Martesia  bowdeniana  (Dali). 

(Plate  26,  Figures  16,  17.) 

Teredina  bowdeniana  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.  Philadelphia, 
vol.  3,  part  4,  pp.  822-823,  plate  36,  fig.  4. 

The  following  is  the  original  description  of  this  species: 

The  specimen  obtained  is  the  portion  of  a  tube  containing  most  of  the 
left  valve  of  a  Teredina,  with  very  marked  sculpture.  The  anterior  border 
is  formed  by  a  narrow,  irregularly  broken  strip  of  the  shelly  matter  belong¬ 
ing  to  the  missing  tube.  The  thin  posterior  border  of  the  valve  is  not 
intact,  though  enough  remains  to  show  the  character  of  the  sculpture.  The 
sculpture  of  the  anterior  part  of  the  valve  is  composed  of  small,  four-sided 
lozenges,  separated  by  sharp,  narrow,  arcuate  grooves  in  such  a  way  as 
to  produce  the  effect  of  a  parting  on  the  periphery  of  the  valve.  This 
grooved  and  faceted  sculpture  ceases  abruptly  behind,  but  the  rows  of  facets 
are  continued  as  wider  longitudinal  riblets  posteriorly.  The  umbonal 
reflection  is  heavy  and  radially  striate;  the  apophysis  seems  to  have  been 
obsolete  and  its  remains  appressed  to  the  internal  arch  of  the  umbo.  The 
whole  is  rather  thick  and  solid,  and  the  antero-posterior  length  of  the 
fragment  is  6.5  millimeters. 

Type  locality. — Bowden,  Jamaica. 

The  holotype — the  anterior  part  of  a  left  valve — is  the  only  speci¬ 
men  of  this  species.  It  fails  to  give  a  definite  idea  of  the  shape  of  the 
shell.  It  probably  is  a  Martesia  rather  than  a  Teredina,  a  genus  that 
occurs  only  in  Eocene  deposits.  The  sculpture  is  similar  to  that  of 
many  species  of  Martesia,  but  the  anterior  threads  are  more  distinctly 
beaded.  The  callus  concealing  the  anterior  gape  is  very  thick  and  its 


PELECYPODS. 


195 


edge  extends  to  the  umbo  under  a  thin  deposit  of  shell  material.  The 
callus  over  the  umbo  completely  conceals  the  umbo  when  viewed  from 
the  interior.  If  the  shell  had  any  myophore  it  is  broken. 

Type  material. — Holotype  (left  valve,  U.  S.  Nat.  Mus.  No.  135737). 

Genus  XYLOPHAGA  Turton. 

Turton,  1822,  Conchylia  Insularum  Britannicarum,  p.  253. 

Type  (by  monotypy). — Teredo  dorsalis  Turton.  Recent,  seas  of 
Europe. 

The  following  is  a  description  of  the  shell  of  the  genus  Xylophaga: 

Shell  medium-sized,  spherical,  posterior  end  widely  gaping;  a  wide, 
deeply  channeled  groove  extends  from  the  umbo  to  the  ventral  margin  at 
the  anterior  end  of  the  gape;  posterior  part  of  shell  sculptured  with  fine 
oblique  threads,  angulated  along  an  oblique  line;  umbos  covered  with  two 
united  shelly  plates ;  myophore  absent. 

Several  doubtful  species  of  these  wood-boring  mollusks  are  recorded 
from  American  Tertiary  deposits. 

Xylophaga  ?  species. 

(Plate  26,  Figure  18.) 

The  anterior  part  of  a  right  valve  in  the  U.  S.  National  Museum 
referred  to  by  Dali,  may  be  a  Xylophaga,  but  its  features  are  indeter¬ 
minable.  The  groove  extending  from  the  umbo  to  the  ventral  margin 
is  wide  and  deeply  channeled.  The  part  of  the  shell  in  front  of  the 
groove  is  sculptured  with  incrementals.  There  is  only  a  small  piece  of 
the  part  of  the  shell  in  back  of  the  groove  preserved.  It  is  worn  and 
its  sculpture  is  obscure. 

Family  TEREDIDAE. 

Genus  TEREDO  Linne. 

Linne,  1758,  Systema  Naturae,  ed.  10,  p.  651. 

Type  (by  subsequent  designation,  Gray,  18/fJ). — Teredo  navalis 
Linne.  Recent,  northern  seas  of  Europe. 

Toredo  ?  species. 

Pieces  of  calcareous  tubes  probably  are  tubes  of  Teredo  or  one  of 
its  allies,  but  no  shells  have  been  found.  They  are  much  smaller  and 
thinner  than  tubes  from  the  Dominican  Republic  to  which  Gabb  gave 
the  name  Kuphus  incrassatus.  It  is  a  common  practice  to  call  Ter¬ 
tiary  tubes  Teredo,  whether  they  are  associated  wTith  wood  or  not. 
Living  species  of  Teredo  make  their  home  in  wood.  Species  of  Kuphus 
Gray  are  said  to  bore  in  sand  and  silt.  Many  of  the  Tertiary  tubes 
may  represent  Kuphus.  Large  tubes,  similar  to  the  Dominican 
Kuphus  incrassatus,  are  remarkably  abundant  in  the  Tertiary  (Eocene 
to  Miocene)  limestones  of  the  West  Indies  and  Central  America, 
especially  in  Anguilla,  Porto  Rico,  Haiti,  Cuba,  Jamaica,  and  Guate- 


196 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


mala.  According  to  available  evidence  these  limestones  were  de¬ 
posited  in  seas  to  which  no  detritus-bearing  streams  had  access. 
Therefore  it  is  not  likely  that  these  numerous  tubes  dropped  from 
rotting  wood. 

Bartsch1  has  recently  published  a  critical  monograph  of  the  Ameri- 
man  species  of  Teredo  and  its  allies,  all  of  which  are  wood-borers.  The 
genera  and  subgenera  are  based  principally  on  features  of  the  pallets, 
which  have  never  been  found  in  a  fossil  state. 


1  P.  Bartsch.  A  monograph  of  the  American  shipworms:  U.  S.  Nat.  Mus.  Bull.,  122,  51  pp. 
37  plates,  1  text-fig.  1922. 


SCAPHOPODS. 


197 


Class  SCAPHOPODA. 

Family  DENTALIIDAE. 

Genus  DENTALIUM  Linne. 

Subgenus  DENTALIUM  s.  s. 

Section  DENTALIUM  s.  s. 

Linne,  1758,  Systema  Naturae,  ed.  10,  p.  785. 

Type  (by  subsequent  designation,  Gray,  18^7). — Dentalium  ele- 
phantinum  Linne.  Recent,  Amboyna  and  Philippine  Islands. 

The  following  is  a  description  of  the  section  Dentalium  s.  s.: 

Shell  medium-sized  or  large,  strongly  curved,  rapidly  enlarging;  sculpture 
consisting  of  strong  longitudinal  ribs;  the  type  species  usually  has  10  (9  to 
11)  primary  ribs,  but  except  at  the  posterior  end  several  secondary  ribs  lie 
in  the  interspaces;  other  species  have  a  varying  number  (4  to  14)  of 
primary  ribs,  increased  by  the  addition  of  secondary  ribs;  the  type  species 
has  a  shallow  notch  on  the  convex  side  of  the  apex;  other  species  have  an 
unnotched  apex. 

Many  subgenera  of  Dentalium,  based  principally  on  apical  features, 
have  been  described.  Although  some  of  them  probably  are  artificial, 
they  serve  a  useful  purpose  in  separating  a  large  group.  The  usage  of 
these  subgenera  as  established  by  Pilsbry  and  Sharp1  and  by  Hender¬ 
son,2  is  here  followed.  Large  or  medium-sized  species  of  Dentalium 
having  strong  longitudinal  ribs,  and  a  shallow  notch  on  the  convex 
side  of  the  apex  or  no  notch,  usually  are  placed  in  the  subgenus 
Dentalium  s.  s.  Tertiary  and  living  species  of  such  Dentalia  have  a 
virtually  cosmopolitan  distribution.  Most  of  the  living  species  inhabit 
shallow  water. 

Key  to  the  Bowden  species  of  Dentalium  s.  s. 

Secondary  ribs  absent  or  very  obscure. 

Primary  ribs  6 .  D.  ( D .)  cossmannianum 

Primary  ribs  8 .  D.  ( D .)  glaucoterrarum 

Primary  ribs  9 . D.  (D.?)  species  a 

Secondary  ribs  present,  primary  ribs  8 . D.  (D.?)  species  b 

Dentalium  (Dentalium)  cossmannianum  Pilsbry  and  Sharp. 

(Plate  27,  Figures  1,  2.) 

Dentalium  dissimile  var  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol.  15, 
p.  244. 

Dentalium  cossmannianum  Pilsbry  and  Sharp,  1898,  Proc.  Acad.  Nat.  Sci. 
Philadelphia,  vol.  49,  pp.  467-468,  plate  10,  fig.  11,  plate  11,  figs.  10,  11. 
Pilsbry  and  Sharp,  1898,  Man.  Conch.,  ser.  1,  vol.  17,  p.  202.  Maury,  1917, 
Bull.  Amer.  Paleontology,  vol.  5,  p.  323,  plate  52,  fig.  3.  Pilsbry,  1922, 
Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  73,  p.  399. 

The  following  is  the  original  description  of  this  species: 

Shell  a  hexagonal  prism  with  slightly  convex  faces,  slender,  slowly  taper¬ 
ing,  moderately  solid,  glossy.  Sculpture:  there  are  6  very  narrow  equidis¬ 
tant  longitudinal  threads,  well  raised  and  sharply  defined,  the  wide  intervals 

1  H.  A.  Pilsbry,  and  B.  Sharp.  Scaphopoda:  Manual  of  Conchology,  ser.  1,  vol.  17.  1897-98. 

*  John  B.  Henderson.  A  monograph  of  the  East  American  Scaphopod  mollusks:  Bull.  U.  S. 
Nat.  Mus.  Ill,  1920. 


198 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


between  them  flat  on  the  smaller  end  of  the  shell,  but  becoming  decidedly 
convex  toward  the  larger  end;  circular  sculpture  of  rather  strongly 
impressed  annular  growth  marks  at  unequal  intervals,  sometimes  close, 
sometimes  distant.  Aperture  not  preserved  in  the  material  before  us, 
but  apparently  not  oblique  and  with  nearly  circular  peristome  but  slightly 
modified  in  shape  by  the  longitudinal  threads.  Apex  not  known,  but 
evidently  hexagonal.  Length  of  (broken)  type  specimen,  23  mm.;  greatest 
diameter  at  larger  end,  3.5,  at  smaller  end,  2.7. 

Type  locality. — Dominican  Republic. 

This  species  is  represented  by  a  number  of  small  broken  pieces.  At 
irregular  intervals  the  growth-lines  are  very  strong.  The  absence  of 
secondary  ribs  is  a  characteristic  feature.  According  to  the  collections 
of  the  U.  S.  Geological  Survey  expedition  this  species  is  confined  to 
the  Gurabo  formation  in  the  Dominican  Republic. 

Other  localities. — Gurabo  formation  (middle  Miocene),  Dominican 
Republic. 

Type  material. — Holotype  (Philadelphia  Acad.  Nat.  Sci.  No.  2709). 

Dentalium  (Dentalium)  glaucoterrarum  Maury. 

(Plate  27,  Figures  3,  4.) 

Dentalium  glaucoterrarum  Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5,  p. 

323,  plate  52,  fig.  4. 

The  following  is  the  original  description  of  this  species: 

Shell  with  8  equal,  distant,  raised  longitudinal  ribs,  intervals  slightly 
convex,  marked  by  irregularly  spaced  circular  growth  lines;  interstitial 
riblets  entirely  absent  or  extremely  weak.  Length  of  fragment,  23  mm.; 
diameter  of  larger  end,  4  mm.;  of  smaller,  3  mm. 

Type  locality. — Zone  E,  Rio  Gurabo  at  Los  Quemados,  Dominican 
Republic. 

This  species,  which  is  represented  by  several  broken  pieces,  is  similar 
to  D.  cossmannianum,  but  has  8  ribs.  At  unequal  intervals  the 
growth-lines  are  strong  like  in  D.  cossmannianum.  Some  specimens 
from  both  Jamaica  and  the  Dominican  Republic  have  obscure  secon¬ 
dary  ribs.  This  species  is  fairly  abundant  in  Cercado  formation,  but 
only  a  few  specimens  have  been  collected  from  the  Gurabo  formation. 

Other  localities. — Cercado  (lower  Miocene)  and  Gurabo  (middle 
Miocene)  formation,  Dominican  Republic. 

Type  material. — Cornell  University. 

Dentalium  (Dentalium?)  species  a. 

(Plate  27,  Figures  5,  6.) 

A  small  broken  Dentalium  resembles  D.  cossmannianum  and  D. 
glaucoterrarum,  but  has  9  ribs.  The  interspaces  are  smooth  except 
for  irregularly  spaced  growth  lines.  The  ribs  are  narrow  and  high, 
making  the  interspaces  convex,  like  on  the  posterior  part  of  D.  coss¬ 
mannianum  and  D.  glaucoterrarum.  This  broken  specimen  probably 
represents  a  new  species  that  may  be  an  Antalis  or  a  Dentalium  s.  s. 


SCAPHOPODS. 


199 


Dentalium  (Dentalium  ?)  species  b. 

(Plate  27,  Figures  7,  8.) 

Several  small  broken  tubes  have  8  primary  ribs  and  1  or  2  secondary 
ribs  in  each  interspace.  At  the  anterior  end  of  the  largest  piece  the 
secondary  ribs  are  almost  as  strong  as  the  primaries.  This  species 
may  be  an  Antalis. 

Section  TESSERACME  Pilsbry  and  Sharp. 

Pilsbry  and  Sharp,  1897,  Manual  of  Conchology,  ser.  1,  vol.  17,  p.  249. 

Type  (by  monotypy) . — Dentalium  quadrapicale  Sowerby.  Recent, 
Cochin  and  Malabar,  Eastern  seas. 

The  following  is  a  description  of  the  section  Tesseracme: 

Shell  medium-sized;  apex  quadrangular,  a  low  primary  rib  at  each  angle; 
the  angles  soon  disappear  and  a  progressively  larger  number  of  secondary 
ribs  are  added  on  the  circular  posterior  two-thirds  of  the  shell;  apex 
unnotched. 

This  curiously  sculptured  group  of  scaphopods  has  an  interesting 
history  similar  to  that  of  many  other  West  Indian  Miocene  mollusks. 
Though  represented  in  the  West  Indies  by  the  Miocene  D.  dissimile 
and  in  Florida  by  the  Pliocene  D.  caloosaenae  Dali,  there  are  no 
living  Atlantic  species.  All  the  known  living  species  are  confined  to 
tropical  and  subtropical  Pacific  waters.  Pilsbry  and  Sharp  have 
already  traced  the  history  of  this  section. 

Key  to  the  Bowden  subspecies  of  Tesseracme. 

Shell  moderately  thick .  D.  ( T .)  dissimile  dissimile 

Shell  very  thick . .  D.  ( T .)  dissimile  ponder osum 

Dentalium  (Tesseracme)  dissimile  dissimile  Guppy. 

(Plate  27,  Figures  9  to  14.) 

Dentalium  dissimile  Guppy,  1866,  Quart.  Jour.  Geol.  Soc.  London,  vol.  22, 
p.  292,  plate  17,  fig.  4.  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol.  15, 
p.  244.  Guppy,  Geol.  Mag.,  dec.  2,  vol.  1,  p.  440  (list).  Guppy,  1876, 
Quart.  Jour.  Geol.  Soc.  London,  vol.  32.  p.  517.  Pilsbry  and  Sharp, 
1898,  Proc.  Acad.  Nat.  Sci.,  Philadelphia,  vol.  49,  pp.  469-470,  plate  11, 
figs.  3  to  5.  Pilsbry  and  Sharp,  1898,  Man.  Conch.,  ser.  1,  vol.  17,  p.  203. 
Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5,  p.  322,  plate  52,  fig.  1. 
Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.,  Philadelphia,  vol.  73,  p.  400. 

Dentalium  ( Tesseracme )  dissimile  Guppy,  Pilsbry,  1911,  Proc.  Acad.  Nat. 
Sci.  Philadelphia,  vol.  63,  p.  166. 

The  following  is  the  original  description  of  this  subspecies: 

t 

Shell  subpolygonal  and  striated  at  the  apex,  becoming  gradually  round, 
smooth,  and  shining  near  the  aperture,  which  is  circular. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  sub¬ 
species  : 

Shell  medium-sized,  thick,  slightly  curved;  apex  rectangular,  the  angles 
elevated  into  low  rounded  ribs  that  soon  disappear  leaving  the  anterior 


200 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


two-thirds  of  the  shell  circular;  near  the  apex  a  secondary  median  rib  lies 
on  each  face  of  the  shell;  a  little  farther  toward  the  anterior  end  1  to  4 
other  secondary  ribs  may  appear;  the  secondary  ribs  disappear  before  the 
primaries  and  the  anterior  two-thirds  of  the  shell  is  smooth  except  for 
obscure  growth  lines. 

Length  51  mm.;  exterior  diameter  of  aperture  4.5  mm.;  arc1  2  mm.  (tip 
broken). 

D.  dissimile  dissimile  and  D.  dissimiie  ponder osum  Gabb  are  the 
largest  and  most  abundant  Bowden  scaphopods.  The  secondary 
sculpture  near  the  apex  varies  in  sharpness  of  detail.  As  Pilsbry  and 
Sharp  have  noted,  the  specimen  figured  by  Guppy  has  only  a  small 
part  of  the  sculptured  anterior  part  of  the  shell.  The  shell  figured 
on  plate  27,  figure  9,  is  not  perfect,  as  a  small  part  of  the  posterior 
end  is  broken.  The  shell  is  larger,  much  thicker,  and  more  uniformly 
curved  than  in  the  type  species  of  the  section.  It  closely  resembles 
D.  tesseragonum  Sowerby,  a  smaller  species  on  the  Pacific  coast  of 
Central  America. 

D.  dissimile  dissimile  is  represented  by  many  specimens  in  the  Cer- 
cado  formation  of  the  Dominican  Republic  and  by  fewer  specimens 
in  the  Gurabo  formation. 

Other  localities. — Cercado  (lower  Miocene)  and  Gurabo  (middle 
Miocene)  formations,  Dominican  Republic. 

Type  material. — Holotype,  British  Museum  (Natural  History), 
Geological  Department,  No.  64082. 

Dentalium  (Tesseracme)  dissimile  ponderosum  Gabb. 

(Plate  27,  Figures  15  to  17.) 

Dentalium  ponderosum  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.,  n.  s.,  vol.  15, 
p.  244. 

Dentalium  dissimile  var.  ponderosum  Gabb,  Pilsbry  and  Sharp,  1898,  Proc. 
Acad.  Nat.  Sci.  Philadelphia,  vol.  49,  p.  470,  plate  10,  figs.  1  to  3,  plate  11, 
figs.  15,  16.  Pilsbry  and  Sharp,  1898,  Man.  Conch.,  ser.  1,  vol.  17,  p.  203. 
Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5,  pp.  322-323,  plate  52,  fig.  2. 

Dentalium  dissimile  ponderosum  Gabb,  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci. 
Philadelphia,  vol.  73,  p.  400. 

The  following  is  the  original  description  of  this  subspecies: 

Shell  elongate,  slender,  very  slightly  arcuate,  the  greater  curve  being  at 
the  tip;  surface  with  a  few  longitudinal  ribs  at  the  apex,  which  become 
obsolete  as  the  shell  grows  older;  beyond  these  there  are  no  ornaments 
except  the  faint  lines  of  growth.  Internally  the  shell  is  thickened  by 
deposition  of  shelly  layers  so  as  to  reduce  the  internal  diameter  to  a  fourth 
of  the  external. 

Type  locality. — Dominican  Republic. 

Length  46  mm.;  exterior  diameter  of  anterior  end  5  mm.;  arc.  1.2  mm. 
(both  ends  broken). 

1  Following  Henderson  the  “arc"  is  a  measure  of  curvature  expressed  by  the  distance  from  a 
line  joining  the  apex  and  aperture  to  the  highest  point  in  the  concave  arch  of  the  lower  surface 
of  the  shell. 


SCAPHOPODS. 


201 


This  subspecies  is  larger  than  D.  dissimile  dissimile  and  its  sculpture 
disappears  more  rapidly.  Its  shell  is  remarkably  thick,  leaving  only  a 
narrow  space  for  the  animal,  except  at  the  aperture  where  the  shell  is 
thin.  The  contrast  between  D.  dissimile  ponder osum  and  D.  dissimile 
dissimile  afforded  by  this  feature  is  strikingly  shown  by  the  sections, 
figures  13,  14,  16,  and  17  on  plate  27.  The  figured  specimen  of  D. 
dissimile  ponderosum  is  broken  at  both  ends  and  all  the  sculptured 
part  is  lost. 

In  the  collections  from  Bowden  this  subspecies  is  less  abundant 
than  D .  dissimile  dissimile.  It  is  represented  in  both  the  Cercado  and 
Gurabo  formations  of  the  Dominican  Republic,  but  like  D.  dissimile 
dissimile  is  more  abundant  in  the  Cercado  formation. 

Other  localities. — Cercado  (lower  Miocene)  and  Gurabo  (middle 
Miocene)  formations,  Dominican  Republic. 

Type  material. — Holotype,  Philadelphia  Acad.  Nat.  Sci.  No.  2708. 

Subgenus  GRAPTACME  Pilsbry  and  Sharp. 

Pilsbry  and  Sharp,  1897,  Manual  of  Conchology,  ser.  1,  vol.  17,  p.  85. 

Type. — Dentalium  eboreum  Conrad.  Recent,  southeastern  United 
States  and  the  West  Indies. 

The  following  is  a  description  of  the  subgenus  Graptacme: 

Shell  small  or  medium-sized,  slender,  moderately  curved,  circular  in 
section;  part  of  shell  near  apex  sculptured  with  very  fine  crowded  longi¬ 
tudinal  riblets,  remainder  of  shell  smooth;  apex  having  a  narrow  notch  on 
convex  side. 

Dentalium  eboreum  is  herewith  designated  the  type  as  none  has 
been  designated. 

As  used  by  Pilsbry  and  Sharp,  the  subgenus  Graptacme  includes 
small  or  medium-sized,  slender  species  having  very  fine  longitudinal 
riblets  near  the  apex.  These  species  have  a  variety  of  apical  features. 
Some  species  have  a  simple  apex;  others  have  a  slit  apical  plug;  others 
have  a  shallow  notch;  and  others  have  a  slit  that  is  on  the  convex 
side,  or  on  the  concave  side,  or  lateral  in  position.  The  living  species 
are  mainly  shallow-water  dwellers  or  live  at  moderate  depths.  They 
are  confined  to  east  and  west  American  waters  and  to  the  Indo-Pacific 
region. 

Key  to  the  Bowden  species  of  Graptacme. 

Apex  having  a  shallow  lateral  notch,  riblets  moderately  crowded . D.  ( G .)  species  a 

Apex  having  a  deep  slit  on  concave  side,  riblets  very  much  crowded. . . D .  (G.)  species  b 

Dentalium  (Graptacme)  species  a. 

Two  small  broken  shells  in  the  Henderson  collection  (U.  S.  Nat. 
Mus.  No.  135534)  represent  a  species  of  Graptacme.  These  shells  are 
very  slender,  circular  in  section,  moderately  thick,  and  slightly  arched. 
The  part  near  the  apex  is  sculptured  with  very  fine  longitudinal 


202 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


riblets  that  soon  disappear,  leaving  most  of  the  shell  smooth.  The 
smaller  of  these  two  pieces  has  a  wide  shallow  lateral  notch. 

Dentalium  (Graptacme)  species  b. 

Another  small  species  of  Graptacme  is  represented  by  an  apical 
piece  in  the  Henderson  collection  (U.  S.  Nat.  Mus.  No.  135535).  This 
species  has  even  finer  and  more  closely  spaced  longitudinal  riblets 
than  species  a.  The  apex  has  a  long  slit,  probably  on  the  concave  side, 
but  the  shell  is  so  small  and  the  curvature  so  slight  that  the  position 
of  the  slit  is  doubtful.  So  far  as  it  goes,  this  fragment  is  similar  to 
D .  (G.)  amaliense  Henderson,  a  living  species  from  St.  Thomas,  but 
has  a  larger  slit  and  more  closely  spaced  riblets.  The  slit  seems  to  be 
unusually  long  for  the  subgenus  Graptacme. 

Subgenus  LAEVIDENTALIUM  Cossmann. 

Cossmann,  1888,  Catalogue  Ulustre  des  Coquilles  Fossiles  de  1’Eocene  des 
Environs  de  Paris,  part  3,  p.  11. 

Type  (by  original  designation). — Dentalium  incertum  Deshayes. 
Eocene,  Paris  Basin.1 

The  following  is  a  description  of  the  subgenus  Laevidentalium: 

Shell  small,  slightly  arched,  slender,  section  slightly  oval;  surface  pol¬ 
ished,  smooth  except  for  obscure  growth  lines;  apex  unnotched. 

This  subgenus  has  been  expanded  by  Pilsbry  and  Sharp  to  serve  as 
a  convenient  division  for  small  or  large,  circular  or  subcircular,  smooth 
species  having  no  apical  notch  or  having  a  shallow  notch  on  the  convex 
side,  as  in  some  species  of  Antalis. 

Dentalium  (Laevidentalium)  hay  tense  Gabb. 

(Plate  27,  Figures  18  to  20.) 

Dentalium  haytensis  Gabb,  1873,  Trans.  Amer.  Philos.  Soc.  n.  s.,  vol  15,  p.  244. 
Pilsbry  and  Sharp,  1898,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  49,  pp. 
471-472,  plate  11,  figs.  8,  9.  Pilsbry  and  Sharp,  1898,  Man.  Conch,  ser.  1, 
vol.  17,  p.  205.  Maury,  1917,  Bull.  Amer.  Paleontology,  vol.  5,  p.  323. 
Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  73,  p.  400. 

?  Dentalium  ( Rhabdus )  sp.  undet.,  Pilsbry,  1911,  Proc.  Acad.  Nat.  Sci.  Phila¬ 
delphia,  vol.  63,  p.  168. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  nearly  straight,  increasing  gradually  in  size,  surface  polished. 

Type  locality. — Dominican  Republic. 

The  following  is  a  description  of  specimens  from  Bowden: 

Shell  medium-sized,  slender,  slightly  arched,  section  circular;  surface 
smooth;  on  polished  shells  obscure  growth-lines  are  visible  passing  around 
the  shell  in  a  slightly  oblique  direction;  apical  features  not  known. 

D.  hay  tense  is  an  almost  featureless  species  represented  by  broken 
pieces  resembling  similar  pieces  from  the  Cercado  and  Gurabo  forma- 

1 1  have  not  seen  authentic  specimens  of  the  type  species.  The  description  is  taken  from 
Cossmann. 


SCAPHOPODS. 


203 


tions  of  the  Dominican  Republic.  Like  most  of  the  other  species  of 
Dentaiium  it  is  more  abundant  in  the  Cercado  formation  than  in  the 
Gurabo.  It  is  the  only  smooth  circular  Dentaiium  from  Bowden. 
The  largest  piece  has  a  diameter  of  3  mm. 

Other  localities. — Cercado  (lower  Miocene)  and  Gurabo  (middle 
Miocene)  formations,  Dominican  Republic. 

Type  material. — Holotype,  Philadelphia,  Acad.  Nat.  Sci.  No.  2715. 

Subgenus  EPISIPHON  Pilsbry  and  Sharp. 

Pilsbry  and  Sharp,  1897,  Manual  of  Conchology,  ser.  1,  vol.  17,  p.  117. 

Type. — Dentaiium  sowerbyi  Guilding.  Recent,  southeastern  United 
States  and  West  Indies. 

The  following  is  a  description  of  the  subgenus  Episiphon: 

Shell  small,  very  slender,  needle-like,  circular,  moderately  curved;  surface 
smooth  except  for  growth  rings  that  are  most  conspicuous  on  posterior  part 
of  shell;  apex  having  a  short  projecting  tube  or  a  wide  shallow  U-shaped 
lateral  notch. 

As  no  type  species  has  been  designated,  Dentaiium  sowerbyi  Guild¬ 
ing,  fully  described  by  Henderson,  is  herewith  designated  the  type. 

Pilsbry  and  Sharp  used  this  subgenus  to  include  small,  thin,  needle- 
shaped  species  of  Dentaiium  having  no  longitudinal  sculpture.  The 
apical  tube,  which  may  not  be  a  feature  of  biologic  significance,  is 
absent  even  on  many  specimens  of  the  type  species  and  is  not  con¬ 
fined  to  species  included  in  this  subgenus.  Most  of  the  living  species 
of  Episiphon  are  deep-water  dwellers. 

Key  to  the  Bowden  species  of  Episiphon. 

Posterior  part  of  shell  sculptured  with  coarse  growth  rings,  section  elliptical. 

D.  ( E .)  schumoi 

Posterior  part  of  shell  not  sculptured  with  coarse  growth  rings,  section  ovate. 

D.  ( E .)  macilentum 

Dentaiium  (Episiphon)  schumoi  Pilsbry. 

(Plate  27,  Figures  21  to  23.) 

Dentaiium  ( Episiphon )  schumoi  Pilsbry,  1911,  Proc.  Acad.  Nat.  Sci.  Phila¬ 
delphia,  vol.  63,  p.  167,  fig.  5. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  slightly  curved,  excessively  slender,  the  adults  but  slightly 
tapering,  young  shells  acicular;  rather  thin;  surface  finely  striated  circu¬ 
larly,  becoming  on  the  posterior  half  strongly  annulated  by  rather  regularly 
spaced,  close  grooves,  slightly  oblique,  and  cutting  the  surface  into  narrow 
segments  much  as  in  D.  ( Fus triaria )  circinatum.  Tube  strongly  compressed 
laterally  throughout;  apex  simple  or  without  a  short  projecting  pipe  or  tube. 
Length  8.2,  antero-posterior  diameter  at  aperture  0.78,  at  apex  0.56  mm.; 
lateral  diameter  at  aperture  0.6,  at  apex  0.46  mm.  The  specimen  has 
evidently  lost  in  length  by  breakage. 

Type  locality. — Bowden,  Jamaica. 


204 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


The  coarse  growth  rings  on  the  posterior  part  of  the  shell  and  the 
lateral  compression  are  characteristic  features  of  this  small,  needle- 
shaped  species.  Some  specimens  have  a  broad  U-shaped  lateral  notch 
similar  to  the  notch  on  some  specimens  of  D.  sowerbyi,  but  deeper.  A 
specimen  figured  by  Pilsbry  has  an  apical  tube. 

Type  material. — Holotype,  Philadelphia  Acad.  Nat.  Sci.  No.  653. 

Dentalium  (Episiphon)  macilentum  Pilsbry. 

(Plate  27,  Figures  24,  25.) 

Dentalium  ( Episiphon )  macilentum  Pilsbry,  1911,  Proc.  Acad.  Nat.  Sci. 

Philadelphia,  vol.  63,  pp.  166-167,  figs.  1,  2. 

The  following  is  the  original  description  of  this  species: 

Shell  small,  moderately  curved,  excessively  slender,  slightly  tapering; 
surface  smooth,  somewhat  glossy,  with  slight  growth-lines  only.  Tube 
very  strongly  compressed  laterally  throughout,  wider  and  thicker  along 
the  concave  than  the  convex  side.  Both  apertures  oval  or  oblong.  Young 
stage  acicular.  Dimensions  of  largest  (though  imperfect)  specimen: 
Length  8.8,  antero-posterior  diameter  at  aperture  9.1,  at  apex  0.7  mm.; 
lateral  diameter  at  aperture  0.7,  at  apex  0.6  mm. 

Type  locality. — Bowden,  Jamaica. 

This  small  species,  which  is  represented  by  many  specimens,  seems 
to  be  a  laterally  compressed  Episiphon.  Most  of  the  specimens  are 
more  compressed  at  the  posterior  end  than  at  the  anterior  end.  The 
apex  of  one  small  specimen  shows  the  base  of  a  projecting  tube  that 
has  been  broken.  The  concave  side  of  the  shell  is  wider  than  the 
convex,  producing  an  ovate  section.  D.  macilentum  is  slightly  larger 
than  D.  schumoi  and  lacks  the  coarse  growth  rings. 

Type  material. — Holotype,  Philadelphia  Acad.  Nat.  Sci.  No.  654. 

Family  SIPHONODENTALIIDAE. 

Genus  CADULUS  Philippi. 

Subgenus  CADULUS  s.  s. 

Philippi,  1844,  Enumeratio  Molluscorum  Sicilae,  vol.  2,  p.  209. 

Type  (by  monotypy). — Dentalium  ovulum  Philippi.  Recent, 
Mediterranean  Sea. 

The  following  is  a  description  of  the  subgenus  Cadulus  s.  s.,  adapted 
from  Pilsbry  and  Sharp : 

Shell  small,  short,  stout,  cask-shaped,  strongly  inflated  medially ;  aperture 
and  apex  subcircular;  apical  opening  not  slit,  contracted  by  a  ledge  inside 
the  opening. 

The  subgenera  of  the  genus  Cadulus ,  as  used  by  Pilsbry  and  Sharp 
and  by  Henderson,  are  based  principally  on  apical  features.  As  only 
a  few  Bowden  specimens  show  apical  features  they  are  classified 
mainly  on  shape  and  similarity  to  living  species.  Species  of  the  sub¬ 
genus  Cadulus  s.  s.  are  characterized  by  their  swollen  outline,  both 
the  dorsal  and  ventral  sides  being  convex,  and  by  their  unslit  apex. 


SCAPHOPODS. 


205 


The  Bowden  species  here  described  seems  to  be  the  only  described 
American  Tertiary  Cadulus  s.  s.  The  living  species  are  confined  to 
the  North  Atlantic  and  adjoining  seas. 

Cadulus  (Cadulus)  simrothi  Pilsbry. 

(Plate  28,  Figure  1.) 

Cadvlus  simrothi  Pilsbry,  1911,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  63, 
pp.  168-169,  fig.  3. 

The  following  is  the  original  description  of  this  species: 

Shell  minute,  smooth,  slightly  arcuate,  biconic,  strongly  swollen  in  the 
middle,  rapidly  tapering  towards  both  ends,  produced  in  a  short  tube  poste¬ 
riorly;  greatest  diameter  contained  about  2%  times  in  the  length  of  the 
shell.  Outline  of  the  most  convex  side  irregular,  the  contours  being  but 
slightly  convex  above  and  below  the  “equator,”  and  sometimes  a  little 
concave  near  the  posterior  orifice;  outline  of  the  opposite  side  similar, 
but  less  convex.  Tube  circular  in  section  at  “equator”  and  aperture, 
decidedly  oval  at  posterior  or  anal  orifice,  being  compressed  on  the  convex 
and  less  on  the  concave  side.  Aperture  much  larger  than  the  other  orifice, 
oblique,  the  peristome  thin.  Anal  orifice  oval,  decidedly  wider  than  long, 
obstructed  by  a  circular  callus  within;  edges  unslit.  Length  2.1  mm.; 
diameter  at  aperture  0.37,  at  greatest  swelling  0.9  mm.;  antero-posterior 
diameter  at  apex  0.27,  lateral  diameter  0.3  mm. 

Type  locality. — Bowden,  Jamaica. 

The  dorsal  side  of  this  species  is  more  evenly  convex  than  the 
ventral  side,  which  bulges  at  the  equator.  This  little  species,  repre¬ 
sented  by  only  a  few  specimens,  is  similar  to  C.  exiguus  Watson  and 
C.  obesus  Watson,  living  West  Indian  species,  but  is  more  inflated 
than  C.  exiguus  and  smaller  than  C.  obesus.  There  is  a  similar  stouter 
undescribed  species  in  the  Gurabo  formation  of  the  Dominican 
Republic. 

Type  material. — Holotype,  Philadelphia  Acad.  Nat.  Sci.  No.  650. 

Subgenus  GADILA  Gray. 

Section  GADILA  s.  s. 

Gray,  1847,  Proceedings  Zoological  Society  of  London,  part  15,  p.  159. 

Type  {by  original  designation). — Dentalium  gadus  Montagu. 
Recent.  According  to  Pilsbry  and  Sharp,  the  habitat  of  this  species 
is  uncertain.  Montagu  gives  “many  parts  of  the  British  channel.” 

The  following  is  a  description  of  the  section  Gadila: 

Shell  small,  moderately  slender,  curved,  the  dorsal  side  convex,  the 
ventral  side  concave,  swollen  between  middle  of  shell  and  aperture;  surface 
smooth  except  for  inconspicuous  growth  lines;  apical  opening  small,  unslit. 

The  subgenus  Gadila  resembles  Cadulus  s.  s.  in  having  an  unslit 
apex,  but  the  shell  is  more  slender  and  more  curved.  The  section 
Gadila  s.  s.  is  further  characterized  by  its  moderately  slender  outline 
and  absence  of  pronounced  sculpture.  There  are  no  Bowden  species 
of  Gadila  s.  s. 


206 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Section  GADILOPSIS,  new  section. 

Type. — Ditrupa  dentalina  Guppy.  Miocene,  Jamaica. 

The  following  is  a  description  of  the  section  Gadilopsis: 

Shell  moderately  small,  very  slender,  needle-shaped,  slightly  swollen  very 
near  aperture;  sculpture  consisting  of  oblique  growth  rings  on  posterior 
part  of  shell;  apical  opening  small,  unslit. 

The  geologic  history  and  present  distribution  of  this  section,  as 
traced  by  Pilsbry  and  Sharp,  seem  to  fully  justify  their  suggestion 
that  the  group  of  C.  dentalinus  should  probably  form  a  separate 
section.  The  needle-shape,  slight  swelling  very  near  the  aperture,  and 
sculpture  separate  Gadilopsis  from  Gadila  s.  s.  The  living  species  of 
sculptured  Gadilopsis  are  confined  to  the  West  Indian  and  adjoining 
waters,  the  Pacific  coast  of  Central  American  and  Mexico,  and  the 
East  Indies.  Pilsbry  and  Sharp  expand  the  group  to  include  similarly 
shaped  . smooth  species. 

Key  to  the  Bowden  species  of  Gadilopsis. 


Shell  very  slender,  growth  rings  crowded .  C.  ( G .)  dentalina 

Shell  relatively  stout,  growth  rings  not  so  crowded .  C.  ( G .)  hendersoni 


Cadulus  (Gadilopsis)  dentalinus  (Guppy). 

(Plate  28,  Figures  2,  3.) 

Ditrupa  dentalina,  Guppy,  1873,  Proc.  Sci.  Assoc.  Trinidad,  vol.  2,  No.  2, 
part  10,  pp.  87-88,  plate  1,  fig.  11.  Guppy,  1874,  Geol.  Mag.,  dec.  2,  vol. 
1,  plate  i6,  fig.  11.  Guppy,  1875,  Geol.  Mag.  dec.  2,  vol.  2,  p.  42. 

Cadulus  dentalinus  (Guppy),  Pilsbry  and  Sharp,  1898,  Man.  Conch,  ser.  1,  vol. 
17,  p.  190,  plate  36,  figs.  21,  22.  Pilsbry,  1911,  Proc.  Acad.  Nat.  Sci.  Phila¬ 
delphia,  vol.  63,  p.  168. 

The  following  is  the  original  description  of  this  species : 

Tube  clavate,  curved,  slightly  irregular  in  diameter,  gradually  increasing 
from  the  smaller  end,  which  is  annulate,  becoming  smooth  towards  the 
middle  of  the  shell;  the  lower  half  smooth,  shining,  rather  suddenly  thick¬ 
ened  near  the  aperture,  to  form  which  it  as  suddenly  contracts  to  a  diameter 
not  greater  than  that  of  the  smaller  third  of  the  tube. 

Type  locality. — Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  small,  needle-shaped,  moderately  curved,  abruptly  inflated  very 
near  aperture,  then  abruptly  sloping  to  aperture,  slightly  flattened  dorso- 
ventrally,  especially  the  posterior  half;  slightly  less  than  posterior  half 
sculptured  with  closely  set  oblique  growth-rings  that  gradually  disappear 
and  become  less  crowded  toward  anterior  end;  aperture  thin,  subcircular; 
apical  opening  small,  subelliptical. 

Length  7  mm.;  greatest  diameter  1  mm. 

Guppy’s  figure  is  unrecognizable.  The  type  material  consists  of  5 
specimens,  only  2  of  which  represent  this  species.  One  of  these  speci¬ 
mens  is  figured.  This  species  closely  resembles  C.  acus  Dali,  a  shallow- 
water  species  from  the  Gulf  of  Mexico  and  the  West  Indies,  and 
C.  panamensis  Pilsbry  and  Sharp,  from  the  Pacific  coast  of  Central 


SCAPHOPODS. 


207 


America.  It  is  a  little  stouter  and  more  abruptly  swollen  than  C.  acus, 
and  more  slender  than  C.  panamensis. 

Cadulus  phenax  Pilsbry  and  Sharp,  from  the  Cercado  formation  of 
the  Dominican  Republic,  has  the  same  general  features,  but  is  less 
abruptly  swollen  near  the  aperture  and  has  less  conspicuous  growth- 
rings.  An  undescribed  species  from  the  Gurabo  formation  of  the 
Dominican  Republic  more  closely  resembles  C.  dentalinus,  but  is  a 
little  stouter. 

Type  material. — 5  cotypes,  only  2  of  which  represent  this  species 
(U.  S.  Nat.  Mus.  No.  115607). 

Cadulus  (Gadilopsis)  hendersoni,  new  species. 

(Plate  28,  Figure  4.) 

The  following  is  a  description  of  this  species: 

Shell  medium-sized,  moderately  slender,  moderately  curved,  gradually 
inflated  near  aperture,  slightly  flattened  dorso-ventrally,  especially  poste¬ 
rior  half;  posterior  half  or  less  sculptured  with  relatively  distant  growth- 
rings;  aperture  subcircular;  apical  opening  subelliptical. 

Length  10  mm. ;  greatest  diameter  1.7  mm. ;  diameter  of  aperture  1.1  mm. ; 
larger  diameter  of  apical  opening  0.5  mm. 

This  species,  represented  only  by  the  holotype,  is  larger  and  stouter 
than  C.  dentalinus  and  has  less  crowded  growth-rings  on  the  sculp¬ 
tured  part.  It  resembles  C.  panamensis  Pilsbry  and  Sharp,  but  is  a 
little  stouter. 

Type  material. — Holotype  (U.  S.  Nat.  Mus.  No.  352724). 

Subgenus  POLYSCHIDES  Pilsbry  and  Sharp. 

Pilsbry  and  Sharp,  1897,  Manual  of  Conchology,  ser.  1,  vol.  17,  p.  146. 

Type  {by  original  designation). — Cadulus  tetraschitus  Watson. 
Recent,  Brazil.1 

The  following  is  a  description  of  the  subgenus  Polyschides: 

Shell  small,  moderately  slender,  moderately  curved,  greatest  swelling 
near  middle,  slightly  contracted  near  aperture;  surface  smooth  except  for 
growth-lines;  apex  having  4  relatively  deep  notches. 

The  relatively  deep  notches  are  characteristic  features  of  this  sub¬ 
genus.  Pilsbry  and  Sharp  extend  its  limits  to  include  species  having 
more  than  4  notches.  The  living  species  are  most  abundant  in  the 
Atlantic. 

Cadulus  (Polyschides)  annulatus  Pilsbry. 

(Plate  28,  Figures  5,  6.) 

Cadulus  annulatus  Pilsbry,  1911,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  63, 

p.  168. 

The  following  is  the  original  description  of  this  species: 

Rather  a  large,  slender  species  of  the  group  of  C.  dentalinus.  The  swell¬ 
ing  is  only  slight  and  near  the  anterior  end;  tube  subcircular  in  section, 


1 1  have  not  seen  the  type  species.  The  description  is  based  on  C.  quadridentatus  Dali. 


208 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


a  trifle  flattened  on  the  convex  side  at  oblique  aperture;  sculpture  of  very 
fine,  close,  oblique  wrinkles  throughout.  The  length  is  about  7.5  mm.; 
greatest  diameter,  1  mm. 

Type  locality. — Bowden,  Jamaica. 

The  following  supplements  the  original  description  of  this  species: 

Shell  moderately  small  and  slender,  greatest  swelling  at  about  anterior 
fourth  of  length,  posterior  half  and  aperture  slightly  flattened  dorso-ven- 
trally;  sculpture  consisting  of  very  fine  oblique  rings,  obscured  by  growth¬ 
lines  on  posterior  half ;  apex  having  2  moderately  deep  notches,  one  on  each 
side  near  the  concave  side,  and  probably  2  shallower  notches  near  the  convex 
side. 

Length  8  mm. ;  greatest  diameter  1.4  mm. 

This  species  is  not  similar  to  C.  dentalinus,  as  it  is  not  abruptly 
inflated  near  the  aperture  and  has  different  apical  features.  The 
broken  apex  of  the  specimen  figured  has  only  2  notches,  but  as  they 
are  not  at  the  middle  of  the  sides,  but  near  the  concave  side,  it  is  not 
likely  that  this  species  is  a  Dischides.  There  are  traces  of  2  other 
shallower  notches.  The  fine  rings,  which  are  most  prominent  on  the 
anterior  part  of  the  shell,  are  a  striking  feature.  Apparently  they  are 
not  growth-rings,  but  actual  sculpture. 

Type  material. — Holotype,  Philadelphia  Acad.  Nat.  Sci.  No.  649. 

Subgenus  PLATYSCHIDES  Henderson. 

Henderson,  1920,  U.  S.  Nat.  Mus.  Bull.  Ill,  p.  104, 

Type  (by  original  designation). — Cadulus  grandis  Verrill.  Recent, 
east  Atlantic  north  of  Hatteras. 

The  following  is  a  description  of  the  subgenus  Platyschides : 

Shell  relatively  large,  moderately  curved,  greatest  swelling  between  mid¬ 
dle  and  aperture,  posterior  part  and  aperture  flattened  dorso-ventrally ; 
surface  smooth  and  polished;  apex  having  4  broad  very  shallow  notches. 

Henderson  extended  the  limits  of  this  subgenus  to  include  species 
having  only  2  shallow  apical  notches.  In  all  the  species  the  notches 
are  shallower  than  in  Polyschides.  This  subgenus  includes  many  Ter¬ 
tiary  and  living  species. 

Key  to  the  Bowden  species  of  Platyschides. 


Dorsal  surface  compressed  near  aperture .  C.  (P.)  depressicolis 

Dorsal  surface  not  compressed  near  aperture 
Shell  relatively  large. 

Greatest  inflation  near  middle,  rapidly  tapering  to  aperture .  C.  (P.)  pilsbryi 

Greatest  inflation  nearer  aperture,  not  rapidly  tapering  to  aperture..  C.  (P.)  species 
Shell  small. 

Shell  compressed  dorso-ventrally .  C.  (P.)  annectens 

Shell  not  compressed  dorso-ventrally . . .  C.  (P.)  arrosus 


SCAPHOPODS. 


209 


Cadulus  (Platyschides)  depressicolis  Pilsbry  and  Sharp. 

(Plate  28,  Figures  7  to  9.) 

Gadus  dominguensis  Gabb,  1873,  (part,  not  d’Orbigny),  Trans.  Amer.  Philos. 
Soc.,  n.  s.,  vol.  15,  p.  245. 

Cadulus  depressicolis  Pilsbry  and  Sharp,  1898,  Proc.  Acad.  Nat.  Sci.  Phila¬ 
delphia,  vol.  49,  pp.  473-474,  plate  11,  figs.  25  to  27.  Pilsbry  and  Sharp, 
1898,  Mam.  Conch,  ser.  1,  vol.  17,  p.  236.  Pilsbry,  1911,  Proc.  Acad.  Nat. 
Sci.  Philadelphia,  vol.  63,  p.  168.  Pilsbry,  1922,  Proc.  Acad.  Nat.  Sci. 
Philadelphia,  vol.  73,  p.  401. 

The  following  is  the  original  description  of  this  species: 

Shell  long  and  slender,  arcuate,  much  compressed  between  the  concave 
and  convex  sides  throughout.  Regularly  and  slowly  enlarging  from  the 
apex  nearly  to  the  aperture,  then  noticeably  contracted  on  all  sides;  on 
the  middle  of  the  convex  side  having  a  distinctly  compressed,  concave  area 
about  one-third  the  width  of  the  shell,  and  extending  from  the  peristome 
backward  a  distance  about  equal  to  the  greatest  diameter  of  the  aperture; 
surface  smooth  and  glossy.  Aperture  oblong;  apex  oblong,  simple,  with 
subcircular  orifice.  Length  11.75  mm.;  greatest  diameter  of  tube  1.63, 
least  diameter  at  same  point  1.25  mm.;  aperture,  greatest  diameter,  1.06; 
least,  0.8  mm. 

Type  locality. — Dominican  Republic. 

All  the  Bowden  specimens  are  broken.  The  one  figured  represents 
about  the  anterior  two-thirds  of  a  shell.  One  specimen  examined  has 
indications  of  4  unsymmetrically  arranged  shallow  apical  notches,  but 
they  may  not  actually  be  notches.  The  depressions  on  the  convex 
side  near  the  aperture  is  a  striking  feature,  apparently  not  represented 
in  any  living  species.  The  dorsal  surface  of  C.  poculum  Dali,  a  living 
West  Indies  species,  is  remarkably  flattened  near  the  aperture,  but  not 
actually  depressed. 

The  holotype  in  the  Gabb  collection  is  the  only  known  specimen 
from  the  Dominican  Republic.  Its  age  is  not  known. 

Other  localities. — Dominican  Republic. 

Type  material. — Holotype  (Philadelphia  Acad.  Nat.  Sci.  No.  2884). 

Cadulus  (Platyschides)  pilsbryi,  new  species. 

(Plate  28,  Figure  10.) 

The  following  is  a  description  of  this  species: 

Shell  moderately  large,  moderately  stout,  gently  curved,  greatest  inflation 
between  middle  and  anterior  end,  rapidly  tapering  to  aperture,  posterior 
and  anterior  parts  moderately  flattened  dorso-ventrally ;  surface  smooth 
and  polished;  aperture  oblique,  elliptical;  apical  features  not  known. 

Length  8  mm.  (without  tip) ;  greatest  diameter  2  mm.;  greatest  diameter 
of  aperture  1.2  mm. 

C.  pilsbryi  is  represented  by  a  number  of  broken  specimens.  Its 
greatest  inflation  is  more  posterior  than  in  C.  depressicolis ;  the  shell 
is  less  flattened,  and  the  dorsal  surface  is  not  depressed  near  the 
aperture.  It  closely  resembles  C.  agassizi  Dali,  a  living  species  from 


210 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


the  southeastern  coast  of  the  United  States,  but  is  more  flattened  and 
tapers  more  rapidly  to  the  aperture.  The  greatest  inflation  is  more 
posterior  than  in  C.  thallus  Conrad,  a  Miocene  species  from  the  Atlan¬ 
tic  States,  and  the  curvature  is  greater. 

Type  material. — Holotype,  U.  S.  Nat.  Mus.  No.  352726. 

Cadulus  (Platyschides)  species. 

An  imperfect  specimen  in  the  U.  S.  National  Museum  collection 
(No.  61568)  represents  a  moderately  large  Platyschides  that  is  more 
slender  than  C.  pilsbryi,  and  its  greatest  inflation  is  more  anterior.  It 
is  more  flattened  than  C.  agassizi  Dali. 

Cadulus  (Platyschides)  annectens,  new  species. 

(Plate  28,  Figure  11.) 

The  following  is  a  description  of  this  species: 

Shell  small,  slender,  slightly  curved,  greatest  inflation  near  middle,  gradu¬ 
ally  tapering  toward  aperture,  then  abruptly  constricted  at  aperture,  flat¬ 
tened  dorso-ventrally,  especially  in  posterior  part;  surface  smooth  and 
polished,  but  obscure  growth-marks  are  visible  on  parts  of  shell;  aperture 
subcircular;  apical  features  not  known. 

Length  5  mm.;  greatest  diameter  1.2  mm.;  diameter  of  aperture  0.6  mm. 

This  small  species,  which  may  be  a  Polyschides ,  is  represented  only 
by  the  holotype.  It  is  much  larger  than  C.  colobus  Pilsbry  and  Sharp 
from  the  Cercado  formation  of  the  Dominican  Republic,  and  its 
anterior  part  is  more  inflated.  The  rapid  taper  at  the  aperture  is  a 
characteristic  feature  of  C.  annectens. 

Type  material. — Holotype  (U.  S.  Nat.  Mus.  No.  353077). 

Cadulus  (Platyschides)  arrosus,  new  species. 

(Plate  28,  Figure  12.) 

The  following  is  a  description  of  this  species: 

Shell  small,  slender,  slightly  curved,  greatest  inflation  rather  abrupt  at 
about  anterior  third  of  length;  section  subcircular  except  at  aperture; 
surface  smooth  and  polished;  aperture  slightly  oblique,  laterally  subellip¬ 
tical;  apical  features  not  known. 

Length  5.5  mm.;  greatest  diameter  1.2  mm.;  greatest  diameter  of  aperture 
0.7  mm. 

This  species,  also  known  only  from  the  holotype,  is  the  only  circular 
Bowden  Platyschides ,  although  the  aperture  is  subelliptical.  In  gen¬ 
eral  features  it  resembles  the  living  West  Indian  C.  portoricensis  Hen¬ 
derson,  but  is  smaller  and  its  inflation  is  more  abrupt.  It  is  smaller 
than  C.  denticulus-tigris  Maury,  from  the  Cercado  formation  of  the 
Dominican  Republic,  and  its  greatest  inflation  is  more  anterior. 

Type  material. — Holotype  (U.  S.  Nat.  Mus.  No.  353078). 


NOTE. 


Doctor  Maury’s  report  describing  Miocene  moilusks  from  Trinidad1 
was  distributed  when  the  page  proof  of  this  report  was  ready  for  the 
printer.  The  only  copy  available  at  the  present  time  is  imperfect,  as 
pages  211  to  218  are  missing.  As  Doctor  Maury  states,  the  Miocene 
deposits  of  Trinidad  contain  very  few  Bowden  species.  The  record  of 
Leda  peltella  Dali  from  the  Cadulus  bed  on  the  Corosal  road  is  based 
on  Guppy’s  record  of  Leda  acuta  Gabb.  As  no  specimens  from  this 
locality  are  in  the  Guppy  collection  at  the  United  States  National 
Museum,  this  record  can  not  be  confirmed.  The  same  statement 
applies  to  Corbula  heterogena  Guppy,  recorded  by  Guppy  from  the 
same  locality.  What  Maury  calls  Glycymeris  jamaicensis  Dali,  from 
a  locality  near  Machapoorie,  has  radial  ribs  that  are  too  strong  for 
jamaicensis .  Glycymeris  jamaicensis  machapoorensis  Maury  is  very 
similar  to  Glycymeris  jamaicensis  jamaicensis,  as  is  shown  by  speci¬ 
mens  in  the  United  States  National  Museum  from  Machapoorie 
quarry,  the  type  locality.  A  worn  shell  from  a  locality  near  Brasso  is 
identified  as  “Scapharca”  inaequilateralis  Guppy,  but  a  shell  from  the 
Dominican  Republic  is  figured.  Ostrea  messor  Maury  is  similar  to 
the  species  here  described  as  0.  paramegodon,  but  is  more  like  0. 
megodon  Hanley.  Specimens  of  Crassinella  guppyi  Dali  from  Spring- 
vale  in  the  United  States  National  Museum,  like  the  specimen  figured 
by  Maury,  are  not  quite  so  inflated  as  specimens  from  Bowden  and 
have  fewer  coarse  lamellae.  The  left  valve  of  Chama  involuta  Guppy 
from  Brasso  Creek  has  essentially  the  same  kind  of  sculpture  as  shells 
from  Bowden,  but  is  more  equilateral.  Similar  poorly  preserved  shells 
from  Machapoorie  quarry  are  in  the  United  States  National  Museum. 
In  addition  to  these  species  Maury  describes  a  number  of  Bowden 
shells  that  have  never  been  found  in  Trinidad. 

Doctor  Maury  renames  Pecten  vaughani  Cooke  1919  and  Pecten 
vaughani  flabellum  Cooke  1919  (not  Pecten  ( Lyropecten )  vaughani 
Arnold  1906),  although  Doctor  Cooke  had  already  renamed  them.2 

1  Carlotta  Joaquina  Maury,  March  27,  1925.  A  further  contribution  to  the  paleontology  of 
Trinidad;  Miocene  horizons.  Bull.  Amer.  Paleontology,  vol.  10,  pp.  152-402,  pis.  12  to  54. 

*C.  Wythe  Cooke,  1921.  New  names  for  West  Indian  Tertiary  Pectens.  Nautilus,  vol. 
34,  No.  4,  p.  137. 


211 


DESCRIPTIONS  OF  PLATES. 

(Unless  otherwise  designated  all  specimens  are  from  Bowden,  Jamaica.) 

PLATE  1. 

Fig.  1.  Nucula  ( Nucula )  morantensis,  n.  sp.  Exterior  of  left  valve  of  holotype  (both  valves 
in  attached  position),  X  4;  U.  S.  Nat.  Mus.  No.  352727;  page  13. 

Figs.  2,  3.  Nucula  (Nuculopsis)  hilli,  n.  sp.  Holotype  (right  valve),  X  2;  (2)  exterior  and 
(3)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352728;  page  14. 

Figs.  4,  5.  Leda  ( Saccella )  peltella  Dali.  Holotype  (right  valve),  X  4;  (4)  exterior  and  (5) 
interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  135753;  page  16. 

Figs.  6,  7.  Leda  ( Saccella )  subcerata,  n.  sp.  Holotype  (right  valve),  X  4;  (6)  exterior  and 
(7)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352729;  page  17. 

The  chondrophore  is  so  small  and  deeply  inset  that  it  is  visible  only  when 
viewed  from  below. 

Figs.  8  to  10.  Leda  ( Saccella )  indigena  Dali.  (8)  Exterior  of  cotype  (right  valve,  cotype  of 
Leda  bisulcata  Guppy),  X  4;  U.  S.  Nat.  Mus.  No.  115553;  (9)  exterior  and 
(10)  interior  of  full-grown  left  valve  X  4;  U.  S.  Nat.  Mus.  No.  352730; 
page  17. 

Figs.  11,  12.  Leda  ( Jupiteria )  bowdenensis  bcwdenensis  n.  sp.  and  subsp.  Holotype  (right 
valve),  X  4;  (11)  exterior  and  (12)  interior  of  same  specimen;  U.  S.  Nat. 
Mus.  No.  352731;  page  19. 

Figs.  13,  14.  Leda  ( Jupiteria )  bowdenensis  subtumida,  n.  subsp.  Holotype  (right  valve), 
X  4;  (13)  exterior  and  (14)  interior  of  same  specimen;  U.  S.  Nat.  Mus. 
No.  352732;  page  19. 

Figs.  15,  16.  Leda  ( Jupiteria )  duerdeni,  n.  sp.  Holotype  (left  valve),  X  4;  (15)  exterior 
and  (16)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352733;  page  19. 

Figs.  17  to  19.  Leda  ( Pseudoportlandia )  clara  Guppy.  (17)  Exterior  of  cotype  (right  valve), 
X  4;  U.  S.  Nat.  Mus.  No.  115558;  (18)  exterior  and  (19)  interior  of  full- 
grown  left  valve,  X  4;  U.  S.  Nat.  Mus.  No.  352734;  page  20. 

Figs.  20,  21.  Yoldia  ( Orthoyoldia )  ovalis  Gabb.  (20)  Exterior  of  right  and  (21)  interior  of 
left  valves,  X  4;  U.  S.  Nat.  Mus.  No.  135751;  page  22. 

Figs.  22,  23.  Tindaria  ( Tindaria )  species.  (22)  Exterior  and  (23)  interior  of  left  valve, 
X  10;  U.  S.  Nat.  Mus.  No.  352735;  page  23. 

PLATE  2. 

Figs.  1  to  3.  Glycymeris  ( Glycymeris )  jamaicensis  Dali.  (1)  Exterior  of  cotype  (right  valve), 
X  1.5;  U.  S.  Nat.  Mus.  No.  135762;  (2)  exterior  and  (3)  interior  of  left 
valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  352736;  page  24. 

Figs.  4,  5.  Glycymeris  ( Glycymeris )  acuticostata  plasia,  n.  subsp.  Holotype  (left  valve), 
X  1.5;  (4)  exterior  and  (5)  interior  of  same  specimen;  U.  S.  Nat.  Mus. 
No.  352737;  page  25. 

Figs.  6,  7.  Glycymeris  ( Glycymerella )  prepennacea,  n.  sp.  Holotype  (left  valve),  X  1.5; 

(6)  exterior  and  (7)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
352738;  page  27.  Anterior  part  of  hinge  defective,  due  to  holes  made  by 
a  boring  animal. 

Figs.  8,  9.  Area  (Area)  occidentals  Phillippi.  (8)  Exterior  and  (9)  interior  of  left  valve, 
X  1;  U.  S.  Nat.  Mus.  No.  352739;  page  29. 

Figs.  10,  11.  Area  (Area)  umbonata  morantensis ,  n.  subsp.  Holotype  (left  valve),  X  1.5; 

(10)  exterior  and  (11)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
352740;  page  30.  In  figure  10  the  upper  part  of  the  shell  is  tilted  a  little 
forward. 

PLATE  3. 

Figs.  1  to  4.  Area  (Area)  bowdeniana  Dali.  (1)  Exterior  and  (2)  interior  of  holotype  (right 
valve),  X  2;  U.  S.  Nat.  Mus.  No.  61621;  (3)  exterior  and  (4)  dorsal  views 
of  larger  right  valve,  X  2;  U.  S.  Nat.  Mus.  No.  352741;  page  31. 

Figs.  5,  6.  Area  (Area)  yaquensis  berryi ,  n.  subsp.  Holotype  (right  valve),  X  2;  (5) 
exterior  and  (6)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352742; 
page  32. 


212 


DESCRIPTIONS  OF  PLATES. 


213 


Figs.  7,  8.  Barbatia  ( Barbatia )  islopa,  n.  sp.  Holotype  (right  valve),  X  1.5;  (7)  exterior 
and  (8)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352743;  page  34. 

Fig  .  9,  10.  Barbatia  ( Barbatia )  propertua ,  n.  sp.  Holotype  (right  valve),  X  3;  (9)  exterior 
and  (10)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352744  page  34. 

Figs.  11,  12.  Barbatia  ( Barbatia )  delepida,  n.  sp.  Holotype  (left  valve),  X  3;  (11)  exterior 
and  (12)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352745;  page 
34. 

Figs.  13,  14.  Barbatia  ( Barbatia )  endomena ,  n.  sp.  Holotype  (right  valve),  X  2;  (13) 
exterior  and  (14)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352746; 
page  35. 

Figs.  15,  16.  Barbatia  ( Barbatia )  inusitata ,  n.  sp.  Holotype  (right  valve),  X  1.5;  (15) 
exterior  and  (16)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352747; 
page  35. 

Figs.  17,  18.  Barbatia  ( Acar )  domingensis  Lamarck.  (17)  Exterior  and  (18)  interior  of 
left  valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  352748;  page  37.  The  hinge  and 
cardinal  area  are  covered  with  a  calcareous  crust. 

Figs.  19,  20.  Barbatia  ( Obliquarca )  dentera,  n.  sp.  Holotype  (left  valve),  X  1.5;  (19) 
exterior  and  (20)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352749; 
page  39. 

Figs.  21,  22.  Barbatia  ( Obliquarca )  subcandida,  n.  sp.  Holotype  (right  valve),  X  2;  (21) 
exterior  and  (22)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352750; 
page  39. 

Figs.  23,  24.  Barbatia  ( Obliquaica )  modiolida,  n.  sp.  Holotype  (left  valve),  X  4;  (23) 
exterior  and  (24)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352751; 
page  40. 

PLATE  4. 

Figs.  1,  2.  Area  antiquata  Linne.  Holotype  (left  valve);  (1)  interior,  slightly  enlarged, 
and  (2)  dorsal,  slightly  reduced,  views  of  same  specimen;  Linnean 
Society  of  London;  locality  unknown. 

Figs.  3.  4.  Barbatia  ( Diluvarca )  halidonata  halidonata  (Dali).  Cotype  (left  valve),  X  1; 

(3)  exterior  and  (4)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
135756;  page  42. 

Figs.  5,  6.  Barbatia  ( Diluvarca )  halidonata  oresta ,  n.  subsp.  Holotype  (right  valve),  X 
1;  (5)  exterior  and  (6)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
352752;  page  43. 

Fig.  7.  Barbatia  ( Diluvarca )  perplura,  n.  sp.  Holotype  (left  valve),  X  1.5;  exterior;  U.  S. 
Nat.  Mus.  No.  352753;  page  44. 

Fig.  8.  Barbatia  ( Diluvarca )  prephina,  n.  sp.  Holotype  (right  valve),  X  1.5;  exterior; 
U.  S.  Nat.  Mus.  No.  352754;  page  44. 

PLATE  5. 

Figs.  1  to  3.  Barbatia  ( Diluvarca )  inaequilaleralis  (Guppy).  (1)  Exterior  and  (2)  interior  of 
largest  of  5  specimens  in  Guppy  collection  labeled  ‘Types/’  (right  valve), 
X  1.5;  U.  S.  Nat.  Mus.  No.  115679;  the  actual  type  material  is  in  the 
British  Museum;  (3)  exterior  of  left  valve,  X  1.5;  U.  S.  Nat.  Mus.  No. 
135763;  page  45. 

Fig.  4.  Barbatia  ( Diluvarca )  dasia,  n.  sp.  Holotype  (left  valve),  X  1.5;  exterior;  U.  S. 
Nat.  Mus.  No.  352755;  page  46. 

Fig.  5.  Barbatia  ( Diluvarca )  wordeni,  n.  sp.  Holotype  (left  valve),  X  1.5;  exterior;  U.  S. 
Nat.  Mus.  No.  352756;  page  46. 

Fig.  6.  Barbatia  ( Diluvarca )  agnastha,  n.  sp.  Holotype  (right  valve),  X  1.5;  exterior; 
U.  >S.  Nat.  Mus.  No.  352757;  page  47. 

Fig.  7.  Barbatia  ( Diluvarca )  themasensis,  n.  sp.  Holotype  (left  valve),  X  2;  exterior; 
U.  S.  Nat.  Mus.  No.  352758;  page  48. 

Figs.  8  to  11.  Barbatia  ( Diluvarca )  dcnacia  (Dali).  (8)  Exterior  and  (9)  interior  of  holotj^pe 
(left  valve),  X  4;  U.  S.  Nat.  Mus.  No.  61628;  (10)  exterior  of  larger  left 
and  (11)  exterior  of  larger  right  valves,  X  4;  U.  S.  Nat.  Mus.  No.  352759; 
page  48. 

Figs.  12,  13.  Barbatia  ( Diluvarca )  microtera,  n.  sp.  Holotype  (left  valve),  X  4;  (12)  exterior 
and  (13)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352760;  page  49. 


214 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Figs.  14,  15.  Barbatia  { Diluvarca )  ophthanta,  n.  sp.  Holotype  (left  valve),  X  4;  (14) 
exterior  and  (15)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352761; 
page  50. 

Figs.  16,  17.  Fossularca  ( Fossularca )  adamsi  sawkinsi ,  n.  subsp.  Holotype  (left  valve), 
X  2;  (16)  exterior  and  (17)  interior  of  same  specimen;  U.  S.  Nat.  Mus. 
No.  352762;  page  51. 

Figs.  18  to  21.  Fossulaica  [Ovalarca)  ovalina  (Dali).  (18)  Exterior  and  (19)  interior  of 
holotype  (left  valve),  X  6;  U.  S.  Nat.  Mus.  No.  135761;  (20)  exterior  and 
(21)  interior  of  right  valve,  X  6;  U.  S.  Nat.  Mus.  No.  352763;  page  52. 

PLATE  6. 

Figs.  1  to  3.  Bathyarca  hendersoni  (Dali).  (1)  Exterior  of  holotype  (left  valve),  X  10;  (2) 
interior  of  different  left  valve,  X  10;  U.  S.  Nat.  Mus.  No.  135760;  (3) 
exterior  of  right  valve  in  attached  position,  X  10;  U.  S.  Nat.  Mus.  No. 
352764;  page  53. 

Figs.  4,  5.  Limopsis  {Pectunculina)  ovalis  silova,  n.  subsp.  Holotype  (left  valve),  X  4; 

(4)  exterior  and  (5)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
352765;  page  55. 

Figs.  6,  7.  Limopsis  { Pectunculina )  jamaicensis,  n.  sp.  Holotype  (left  valve),  X  10;  (6) 
exterior  and  (7)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352766; 
page  55. 

Fig.  8.  Pinna  refurca ,  n.  sp.  Holotype  (broken  left  valve),  X  1.5;  exterior;  U.  S.  Nat.  Mus. 
No.  352767;  page  56. 

Fig.  9.  Alrina  species.  Exterior  of  broken  right  valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  352768; 
page  57. 

Fig.  10.  Isognomon  species.  Interior  of  broken  left  valve,  X  1.5;  U.  S.  Nat.  Mus.  No. 
352769;  page  58. 

Fig.  11.  Pteria  inornata  (Gabb).  Exterior  of  right  valve,  X  2;  U.  S.  Nat.  Mus.  No.  352770; 
page  58. 

Figs.  12  to  14.  Ostrea  { Lopha )  paramegodon ,  n.  sp.  (12)  Exterior  and  (13)  interior  of  holotype 
(right  valve),  1.5;  U.  S.  Nat.  Mus.  No.  352771;  (14)  exterior  of  paratype 
(left  valve),  X  1.5;  U.  S.  Nat.  Mus.  No.  352772;  page  60. 

PLATE  7. 

Figs,  1,2.  Ostrea  {Lopha)  guppyi ,  n.  sp.  Holotype  (right  valve),  X  1.5;  (1)  exterior  and  (2) 
interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352773;  page  61. 

Figs.  3  to  5.  Ostrea  {Lopha)  folioides,  n.  sp.  (3)  exterior  and  (4)  interior  of  holotype  (right 
valve),  X  1.5;  U.  S.  Nat.  Mus.  No.  352774;  (5)  exterior  of  small  left  valve 
having  clasping  spines,  X  1.5;  U.  S.  Nat.  Mus.  No.  352775;  page  61. 

Figs.  6,  7.  Pecten  ( Pecten )  barretti ,  n.  sp.  (6)  Exterior  of  holotype  (right  valve),  X  1;  U.  S. 

Nat.  Mus.  No.  352776;  (7)  exterior  of  paratype  (left  valve  of  a  larger 
shell),  X  1;  U.  S.  Nat.  Mus.  No.  352777;  page  62. 

Figs.  8,  9.  Pecten  { Euvola )  bowdenensis  Dali.  (8)  Exterior  of  cotype  (left  valve),  X  1; 

U.  S.  Nat.  Mus.  No.  135782;  (9)  exterior  of  right  valve,  X  1  U.  S.  Nat. 
Mus.  No.  352778;  page  63. 

Fig.  10.  Chlamys  ( Chlamys )  species.  Exterior  of  right  valve  (anterior  auricle  broken), 

X  6;  U.  S.  Nat.  Mus.  No.  352779;  page  65. 

PLATE  8. 

Figs.  1,  2.  Chlamys  { Chlamys )  vaginulus  (Dali).  (1)  Exterior  of  cotype  (right  valve),  X 
3;  (2)  exterior  of  another  cotype  (left  valve),  X  3;  U.  S.  Nat.  Mus.  No. 
135786;  page  65. 

Fig.  3.  Chlamys  {Chlamys)  bellipictus,  n.  sp.  Holotype  (right  valve),  X  6;  exterior;  U.  S. 
Nat.  Mus.  No.  352789;  page  66. 

Figs.  4,  5.  Chlamys  {Aegui  pecten)  plurincminis  morantensis,  n.  subsp.  (4)  Exterior  of  holo¬ 
type  (right  valve)  X  1;  U.  S.  Nat.  Mus.  No.  352781;  (5)  exterior  of  para¬ 
type  (left  valve),  X  1;  U.  S.  Nat.  Mus.  No.  352782;  page  67. 

Figs.  6,  7.  Chlamys  {Plagioctenium)  uselmae  (Pilsbry  and  Johnson).  (6)  Exterior  of  right 
and  (7)  exterior  of  left  valves;  X  1;  U.  S.  Nat.  Mus.  No.  352783;  page  69. 


DESCRIPTIONS  OF  PLATES. 


215 


Fig.  8.  Chlamys  ( Plagioctenium )  concinnalus,  n.  sp.  Holotype  (left  valve),  X  2;  exterior; 
U.  S.  Nat.  Mus.  No.  352784;  page  70. 

Fig.  9.  Chlamys  ( Plagioctenium )  arneleus,  n.  sp.  Holotype  (right  valve),  X  2;  exterior; 
U.  S.  Nat.  Mus.  No.  352785;  page  70. 

Fig.  10.  Chlamys  ( Plagioctenium )  mansfieldi ,  n.  sp.  Holotype  (left  valve),  X  4;  exterior; 
U.  S.  Nat.  Mus.  No.  352786;  page  71. 

Figs.  11,  12.  Chlamys  ( Plagioctenium )  gonioides ,  n.  sp.  (11)  Exterior  of  holotype  (left 
valve),  X  2;  U.  S.  Nat.  Mus.  No.  352787;  (12)  exterior  of  paratype  (right 
valve),  X  2;  U.  S.  Nat.  Mus.  No.  353076;  page  71. 

Figs.  13  to  16.  Chlamys  ( Palliolum ?)  guppyi  (Dali).  (13)  Exterior  and  (14)  interior  of 
cotype  (left  valve),  X  8;  (15)  exterior  and  (16)  interior  of  another  cotype 
(right  valve),  X  8;  U.  S.  Nat.  Mus.  No.  135779;  page  72. 

PLATE  9. 

Figs.  1,  2.  Amusium  ( Amusium )  papyraceum  Gabb?  (1)  Exterior  and  (2)  interior  of  small 
piece  of  a  large  valve,  X  1;  U.  S.  Nat.  Mus.  No.  135780;  page  73. 

Figs.  3,  4.  Amusium  ( Parvamussium )  spendulum,  n.  sp.  Holotype  (left  valve),  X  6;  (3) 
exterior  and  (4)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352788; 
page  75. 

Figs.  5  to  7.  Spondylus  bostrychites  Guppy.  (5)  Exterior  and  (6)  interior  of  right  valve,  X  1 ; 

U.  S.  Nat.  Mus.  No.  115522.  (7)  exterior  of  smaller  right  valve  having 

wide  primary  ribs,  X  1.5;  U.  S.  Nat.  Mus.  No.  352789;  page  76. 

Fig.  8.  Spondylus  species.  Exterior  of  left  valve,  X  3;  U.  S.  Nat.  Mus.  No.  352790;  page 
77. 

Figs.  9  to  11.  Plicatula  guppyi,  n.  sp.  (9)  Exterior  and  (10)  interior  of  holotype  (right 
valve,  a  cotype  of  Plicatula  vexillata  Guppy),  X  2;  U.  S.  Nat.  Mus.  No. 
115536;  (11)  exterior  of  left  valve,  X  2;  U.  S.  Nat.  Mus.  No.  352791; 
page  78. 

Figs.  12,  13.  Lima  {Lima)  stenacostata,  n.  sp.  Holotype  (left  valve),  X  4;  (12)  exterior  and 

(13)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352792;  page  79. 
Figs.  14,  15.  Lima  ( Mantellum )  species.  (14)  Exterior  and  (15)  interior  of  broken  right 

valve,  X  4;  U.  S.  Nat.  Mus.  No.  352793;  page  80. 

PLATE  10. 

Figs.  1,  2.  Limea  solida  Dali.  Holotype  (left  valve),  X  8.  (1)  Exterior  and  (2)  interior  of 
same  specimen;  U.  S.  Nat.  Mus.  No.  135679;  page  81. 

Figs.  3  to  5.  Placunanomia  lithobleta  Dali.  (3)  Exterior  and  (4)  interior  of  cotype  (broken 
right  valve),  X  1;  (5)  interior  of  another  cotype  (broken  left  valve),  X  1; 
U.  S.  Nat.  Mus.  No.  135778;  page  82. 

Figs.  6  to  9.  Anomia  indecisa  Dali.  (6)  Exterior  and  (7)  interior  of  same  specimen  (large 
left  valve),  X  2;  U.  S.  Nat.  Mus.  No.  352794;  (8)  interior  of  a  broken  left 
valve  and  (9)  interior  of  small  left  valve,  X  2;  U.  S.  Nat.  Mus.  No.  135777; 
page  84. 

Figs.  10  to  12.  Modiolus  ( Brachydontes )  guppyi  Dali.  (10)  Exterior  of  cotype  (left  valve), 
X  4;  (11)  exterior  of  another  cotype  (small  right  valve),  X  4;  U.  S.  Nat. 
Mus.  No.  135747;  (12)  interior  of  right  valve,  X  4;  U.  S.  Nat.  Mus.  No. 
353073;  page  85. 

Figs.  13,  14.  Mytilopsis  jamaicensis,  n.  sp.  Holotype  (left  valve),  X  2;  (13)  exterior  and 

(14)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352795;  page  86. 
Figs.  15,  16.  Julii  gardnerae,  n.  sp.  Holotype  (left  valve),  X  3;  (15)  exterior  and  (16) 

interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352796;  page  88. 

Figs.  17  to  19.  Poromy a  jamaicensis  Dali.  (17)  Exterior  of  holotype  (left  valve),  X  4; 

(18)  interior  of  different  left  valve  and  (19)  interior  of  right  valve,  X  4; 
U.  S.  Nat.  Mus.  No.  135690;  page  88. 

Figs.  20  to  22.  Cuspidaria  ( Cardiomya )  craspedonia  Dali.  3  cotypes,  X  6;  (20)  and  (21) 
exteriors  and  (22)  interior  of  3  different  left  valves;  U.  S.  Nat.  Mus.  No. 
135691;  page  90. 


216 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


PLATE  11. 

Figs.  1  to  5.  Cuspidaria  ( Bowdenia )  distira  Dali.  (1)  Exterior  of  cotype  (left  valve),  X  6; 

(2)  exterior  and  (3)  interior  of  different  left  valve,  X  6;  (4)  exterior  ahd 
(5)  interior  of  right  valve,  X  6;  U.  S.  Nat.  Mus.  135692;  page  91. 

Figs.  6  to  8.  Verticordia  ( Trigonulina )  bowdenensis  Dali.  3  cotypes,  X  6;  (6)  exterior  of 
left  valve;  (7)  interior  of  a  different  left  valve;  (8)  interior  of  right  valve; 
U.  S.  Nat.  Mus.  No.  135689;  page  92. 

Figs.  9  to  11.  Verticordia  ( Haliris )  jamaicensis  Dali.  3  cotypes,  X  6;  (9)  exterior  of  right 
valve;  (10)  interior  of  different  right  valve;  (11)  interior  of  left  valve; 
U.  S.  Nat.  Mus.  No.  135688;  page  93. 

Figs.  12  to  15.  Crassatellites  (Crassatellites)  jamaicensis  Dali.  2  cotypes,  X  1;  (12)  exterior 
and  (13)  interior  of  left  valve;  (14)  exterior  and  (15)  interior  of  smaller 
right  valve;  U.  S.  Nat.  Mus.  No.  135683;  page  94. 

Figs.  16,  17.  Crassatellites  ( Crassatellites )  altaspissus,  n.  sp.  Holotype  (right  valve),  X  1; 

(16)  exterior  and  (17)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
352797;  page  95. 

Figs.  18  to  20.  Crassinella  guppy i  Dali.  (18)  Exterior  of  holotype  (right  valve),  X  6;  U.  S. 

Nat.  Mus.  No.  107151;  (19)  interior  of  different  right  valve,  X  6;  (20) 
interior  of  left  valve,  X  6;  U.  S.  Nat.  Mus.  No.  135684;  page  96. 

PLATE  12. 

Figs.  1  to  4.  Crassinella  bowdenensis  Dali.  (1)  Exterior  of  cotype  (right  valve),  X  6:  (2 
right  valve  of  another  cotype  (both  valves  in  attached  position),  X  6; 

(3)  interior  of  right  and  (4)  interior  of  left  valve,  X  6;  U.  S.  Nat.  Mus. 
135685;  page  97.  In  figure  2  the  shell  is  tilted  to  the  right. 

Figs.  5,  6.  Crassinella  xena,  n.  sp.  Holotype  (left  valve),  X  10;  (5)  exterior  and  (6) 
interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352798;  page  98. 

Figs.  7  to  9.  Cardita  (Gians)  scabriccstata  Guppy.  (7)  Exterior  of  left  valve,  largest  of  17 
specimens  in  Guppy  collection  labeled  “types,”  X  2;  U.  S.  Nat.  Mus. 
No.  115669;  (8)  interior  of  another  left  valve  and  (9)  interior  of  right 
valve,  X  2;  U.  S.  Nat.  Mus.  No.  135676;  page  99.  The  actual  type  is  in 
the  British  Museum. 

Figs.  10  to  12.  Venericardia  ( Pleuromeris )  acaris  Dali.  3  cotypes,  X  6;  (10)  exterior  of 
left  valve;  (11)  interior  of  different  left  valve;  (12)  interior  of  right  valve; 
U.  S.  Nat.  Mus.  No.  135677;  page  102. 

Figs.  13  to  17.  Chama  involuta  Guppy.  (13)  Exterior  and  (14)  interior  of  left  valve,  X  2; 

(15)  exterior  and  (16)  interior  of  right  valve,  X  2;  U.  S.  Nat.  Mus.  No. 
352799;  (17)  exterior  of  left  valve  showing  nepionic  shell,  X  6;  U.  S.  Nat. 
Mus.  No.  352800;  page  103. 

Figs.  18,  19.  Chama  macerophylla  Gmelin.  (18)  Exterior  and  (19)  interior  of  right  valve, 
X  1.5;  U.  S.  Nat.  Mus.  No.  352801;  page  104. 

PLATE  13. 

Figs.  1  to  4.  Echinochama  antiquata  Dali.  (1)  Exterior  and  (2)  interior  of  cotype  (left 
valve),  X  1;  U.  S.  Nat.  Mus.  No.  135740;  (3)  exterior  and  (4)  interior  of 
right  valve,  X  1  U.  S.  Nat.  Mus.  No.  352802;  page  106. 

Figs.  5,  6.  Codqkia  ( Codakia )  spinulosa  Dali.  Holotype  (right  valve),  X  2;  (5)  exterior 
and  (6)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  135713;  page  108 
Figs.  7,  8.  Codakia  ( Codakia )  lomonea ,  n.  sp.  Holotype  (right  valve),  X  2;  (7)  exterior 
and  (8)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352803;  page  108. 

PLATE  14. 

Figs.  1  to  4.  Codakia  ( Jagonia )  vendryesi  Dali.  (1)  Exterior  of  cotype  (right  valve),  X  4; 

(2)  exterior  of  another  cotype  (left  valve),  X  4;  (3)  interior  of  larger  right 
and  (4)  left  valves,  X  4;  U.  S.  Nat.  Mus.  No.  135720;  page  109. 

Figs.  5  to  7.  Codakia  ( Jagonia )  guppyi,  n.  name.  (5)  Exterior  of  cotype  (right  valve,  a 
cotype  of  Lucina  textilis  Guppy),  X  2;  U.  S.  Nat.  Mus.  No.  107103;  (6) 
interior  of  larger  right  valve,  X  2;  U.  S.  Nat.  Mus.  No.  352804;  (7)  interior 
of  left  valve,  X  2;  U.  S.  Nat.  Mus.  No.  135718;  page  110. 


DESCRIPTIONS  OF  PLATES. 


217 


Figs.  8,  9.  Lucina  ( Lucina )  bowdenensis,  n.  sp.  Holotype  (left  valve),  X  1.5;  (8)  exterior 
and  (9)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352805;  page  111. 

Figs.  10  to  12.  Myrtaea  ( Myrtaea )  limoniana  Dali.  (10)  Exterior  and  (11)  interior  of 
holotype  (right  valve),  X  2;  (12)  interior  of  smaller  left  valve,  X  2;  U.  S. 
Nat.  Mus.  No.  157637;  page  112. 

Figs.  13  to  16.  Myrtaea  ( Myrtaeopsis )  pertenera  (Dali).  (13)  Exterior  and  (14)  interior 
of  cotype  (left  valve),  X  1.5;  U.  S.  Nat.  Mus.  No.  135716;  (15)  exterior 
and(16)  interior  of  smaller  right  valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  352806; 
page  113. 

PLATE  15. 

Figs.  1  to  3.  Myrtaea  ( Eulopia )  vermiculata  Dali.  (1)  Exterior  and  (2)  interior  of  holotype 
(right  valve),  X  4;  (3)  interior  of  left  valve,  X  4;  U.  S.  Nat.  Mus.  No. 
135717;  page  114. 

Figs.  4,  5.  Myrtaea  ( Eulopia )  furcata  Dali.  Cotype  (right  valve),  X  2;  (4)  exterior  and  (5) 
interior  of  same  specimen;  U.  8.  Nat.  Mus.  No.  135714;  page  115. 

Fig.  6.  Miltha  ( Megaxinus )  gluminda,  n.  sp.  Holotype,  X  1.5;  exterior;  U.  S.  Nat.  Mus. 
No.  352807;  page  117. 

Fig.  7.  Phacoides  ( Phacoides f)  species.  Exterior  of  broken  right  valve,  X  1.5;  U.  S.  Nat. 
Mus.  No.  135712;  page  117. 

Figs.  8  to  11.  Phacoides  ( Linga )  podagrinus  podagrinus  Dali.  (8)  Exterior  and  (9)  interior 
of  cotype  (right  valve),  X  1.5;  (10)  exterior  of  a  greatly  inflated  right 
valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  135710;  (11)  interior  of  small  left 
valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  135711;  page  119. 

Fig.  12.  Phacoides  (Linga)  podagrinus  alarantus,  n.  subsp.  Holotype  (right  valve),  X  1; 

exterior;  U.  S.  Nat.  Mus.  No.  352808;  page  119. 

* 

PLATE  16. 

Fig.  1.  Phacoides  (Linga)  browni,  n.  sp.  Holotype  (left  valve),  X  1;  exterior;  U.  S.  Nat. 
Mus.  No.  352809;  page  120. 

Figs.  2,  3.  Phacoides  (Linga)  tithonis  Dali.  Holotype  (right  valve),  X  6;  (2)  exterior  and 
(3)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  135723;  page  120. 

Figs.  4  to  6.  Phacoides  (Pleurolucina)  quadi  icostatus  Dali.  Holotype  (left  valve),  X  6;  (4) 
exterior,  (5)  interior,  and  (6)  lateral  views  of  same  specimen;  U.  S.  Nat. 
Mus.  No.  135722;  page  121. 

Figs.  7,  8.  Phacoides  (Cardiolucina)  recurrens  Dali.  Holotype  (right  valve),  X  4;  (7)  exterior 
and  (8)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  135721;  page  122. 

Figs.  9  to  13.  Phacoides  (Callucina)  pauperatus  pauperatus  Guppy.  (9)  Exterior  and  (10) 
interior  of  cotype  (small  left  valve),  X  2;  U.  S.  Nat.  Mus.  No.  107101; 
(11)  exterior  and  (12)  interior  of  larger  left,  and  (13)  interior  of  right 
valves,  X  2;  U.  S.  Nat.  Mus.  No.  135715;  page  123. 

Figs.  14,  15.  Phacoides  (Callucina)  pauperatus  oligocostatus,  n.  subsp.  Holotype  (right 
valve),  X  2;  (14)  exterior  and  (15)  interior  of  same  specimen;  U.  S.  Nat. 
Mus.  No.  352810;  page  124. 

Figs.  16,  17.  Phacoides  (Callucina)  eury costatus,  n.  sp.  Holotype  (left  valve),  X  4;  (16) 
exterior  and  (17)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352811; 
page  124. 

PLATE  17. 

Figs.  1,  2.  Phacoides  (Parvilucina)  yaquensis  morantensis,  n.  subsp.  Holotype  (right  valve), 
X  6;  (1)  exterior  and  (2)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
352812;  page  125. 

Figs.  3,  4.  Phacoides  (Parvilucina)  limnidus,  n.  sp.  Holotype  (right  valve),  X  6;  (3)  ex¬ 
terior  and  (4)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352813; 
page  126. 

Figs.  5  to  8.  Phacoides  (Dellucina)  actinus  Dali.  4  cotypes,  X  6;  (5)  exterior  of  right  valve; 

(6)  interior  of  different  right  valve;  (7)  exterior  of  left  valve;  (8)  interior  of 
different  left  valve;  U.  S.  Nat.  Mus.  No.  135719;  page  126. 

Figs.  9  to  13.  Divaricella  (Divaricella)  prevaricata  (Guppy).  (9)  Exterior  and  (10)  interior 
of  holotype  (small  left  valve),  X  2;  (11)  interior  of  larger  right  valve, 
X  2;  U.  S.  Nat. Mus.  No.  107102;  (12)  exterior  and  (13)  interior  of  larger 
left  valve,  X  2;  U.  S.  Nat. Mus.  No.  352814;  page  128. 


218 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Figs.  14,  15.  Diplodonta  ( Diplodonta )  walli,  n.  sp.  Holotype  (right  valve),  X  6;  (14)  ex¬ 
terior  and  (15)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352815; 
page  129. 

Figs.  16,  17.  Diplodonta  ( Diplodonta )  homalostriata,  n.  sp.  Holotype  (right  valve),  X  6; 

(16)  exterior  and  (17)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
352816;  page  129. 

Figs.  18  to  21.  Diplodonta  ( Felaniella )  minor  Dali.  (18)  Exterior  and  (19)  interior  of 
holotype  (left  valve),  X  6;  (20)  exterior  and  (21)  interior  of  right  valve, 
X  6;  U.  S.  Nat.  Mus.  No.  135724;  page  130. 

PLATE  18. 

Figs.  1  to  3.  Diplodonta  { Phlyctiderma )  gabbi  Dali.  (1)  Exterior  and  (2)  interior  of  right 
valve  (cotype  of  D.  puncturella  Dali),  X  6;  (3)  exterior  of  left  valve 
(another  cotype  of  D.  punctmella  Dali),  X  6;  U.  S.  Nat.  Mus.  No.  155744; 
page  131. 

Figs.  4,  5.  Erycina  ( Erycina )  olssoni ,  n.  sp.  Holotype  (right  valve,  a  specimen  in  Hen¬ 
derson  collection  labeled  Erycina  quadrata  Gabb),  X  6;  (4)  exterior  and 
(5)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  135687;  page  132. 

Figs.  6,  7.  Erycina  ( Erycina )  pur  a  n.  sp.  Holotype  (right  valve),  X  6;  (6)  exterior  and 
(7)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352817;  page  133. 

Figs.  8,  9.  Neaeromya  menotreta,  n.  sp.  Holotype  (left  valve),  X  6;  (8)  exterior  and  (9) 
interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352818;  page  133. 

Figs.  10,  11.  Cardium  ( Acanthocardia ?)  dissidepictum ,  n.  sp.  Holotype  (left  valve),  X  1.5; 

(10)  exterior  and  (11)  interior  of  same  specimen;  U.  S.  Nat.  Mus. 
No.  352819;  page  135.  The  anterior  cardinal  of  this  specimen  is  broken  off. 

Figs.  12,  13.  Cardium  ( Trachycardium )  lingualeonis  Guppy.  (12)  Exterior  and  (13)  interior 
of  right  valve,  X  1;  U.  S.  Nat.  Mus.  No.  352820;  page  136. 

Figs.  14  to  16.  Cardium  ( Trachycardium )  bowdenense  Dali.  (14)  Exterior  of  small  left 
valve  (probably  cotype,  but  not  so  labeled,  1  of  2  specimens  in  Guppy 
collection  originally  labeled  C.  muricatum  Linn6),  X  2;  U.  S.  Nat.  Mus. 
No.  115667;  (15)  exterior  and  (16)  interior  of  larger  right  valve,  X  2 
U.  S.  Nat.  Mus.  No.  352821;  page  137. 

PLATE  19. 

Figs.  1,  2.  Cardium  ( Trachycardium )  inconspicuum  Guppy.  (1)  Exterior  and  (2)  interior 

of  right  valve,  X  1;  U.  S.  Nat.  Mus.  No.  135730;  page  138. 

Figs.  3,  4.  Cardium  ( Trachycardium )  waylandi,  n.  sp.  Holotype  (right  valve),  X  1;  (3) 
exterior  and  (4)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352822; 
page  139. 

Figs.  5,  6.  Cardium  ( Fragum )  medium  LinnA  (5)  Exterior  and  (6)  interior  of  right  valve, 
X  1;  U.  S.  Nat.  Mus.  No.  352823;  page  140. 

Fig.  7.  Cardium  ( Fragum )  elattocostatum ,  n.  sp.  Holotype  (right  valve),  X  4;  exterior; 
U.  S.  Nat.  Mus.  No.  352824;  page  141. 

Figs.  8,  9.  Cardium  ( Trigoniocardia )  haitense  haitense  Sowerbv.  (8)  Exterior  and  v9)  in¬ 
terior  of  left  valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  352825;  page  142. 

Figs.  10,  11.  Cardium  ( Trigoniocardia )  haitense  cercadicum  Maury.  (10)  Exterior  and  (11) 
interior  of  left  valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  352826;  page  143.  In 
figure  10  the  shell  is  tilted  to  the  left. 

Figs.  12,  13.  Cardium  ( Trigoniocardia )  thaumastum ,  n.  sp.  Holotype  (right  valve),  X  2; 

(12)  exterior  and  (13)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
352827;  page  144. 

Figs.  14-16.  Cardium  ( Laevicardium )  serratum  Linne.  (14)  Exterior  of  broken  left  valve, 
X  1;  U.  S.  Nat.  Mus.  No.  135728;  (15)  exterior  and  (16)  interior  of 
smaller  left  valve,  X  1;  U.  S.  Nat.  Mus.  No.  352828;  page  145. 

Fig.  17.  Protocardia  ( Nemocardium )  jamaicensis  Dali.  Holotype  (left  valve),  X  4;  ex¬ 
terior;  U.  S.  Nat.  Mus.  No.  135733;  page  147. 

PLATE  20. 

Figs.  1-5.  Pliocardia  bowdeniana  (Dali).  (1)  Exterior  of  holotype  (small  right  valve),  X  4-, 
U.  S.  Nat.  Mus.  No.  135671;  (2)  exterior  and  (3)  interior  of  full-grown 
right  valve,  X  4;  (4)  exterior  and  (5)  interior  of  full-grown  left  valve, 
X  4;  U.  S.  Nat.  Mus.  No.  352829;  page  148. 


DESCRIPTIONS  OF  PLATES. 


219 


Figs.  6,  7.  Tivela  ( Tivela )  jamaicensis  Dali.  Holotype  (left  valve),  X  4;  (6)  exterior  and 
(7)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  135675;  page  149. 

Figs.  8-10.  Gafrarium  ( Gouldia )  insulare  Dali  and  Simpson.  (8)  Exterior  and  (9)  interior 
of  right  valve,  and  (10)  interior  of  left  valve,  X  4;  U.  S.  Nat.  Mus.  No. 
135674;  page  150. 

Figs.  11,  12.  Callocardia  ( Callocardia )  ammondea,  n.  sp.  Holotype  (left  valve),  X  4;  (11) 
exterior  and  (12)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352830; 
page  151. 

Figs.  13,  14.  Callocardia  ( Callocardia )  elethusa,  n.  sp.  Holotype  (left  valve),  X  4;  (13) 
exterior  and  (14)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352831; 
page  152. 

Figs.  15  to  19.  Pitar  ( Hyphantosoma )  carbaseus  (Guppy).  (15)  Exterior  and  (16)  interior 
of  broken  right  valve,  X  1;  (17)  exterior  and  (18)  interior  of  broken  left 
valve,  X  1;  (these  2  specimens  from  the  Guppy  collection  are  labeled, 
“types,”  though  the  actual  type  is  in  the  British  Museum);  U.  S.  Nat. 
Mus.  No.  115552;  (19)  exterior  of  right  valve,  X  1;  U.  S.  Nat.  Mus.  No. 
No.  352832;  page  153. 

PLATE  21. 

Figs.  1  to  4.  Pitar  ( Hysteroconcha )  planivietus  (Guppy).  (1)  Exterior  of  right  and  (2) 
exterior  of  left  valve,  X  1 ;  (these  2  specimens  from  the  Guppy  collection 
are  labeled  “types,”  though  the  actual  type  is  in  the  British  Museum); 
U.  S.  Nat.  Mus.  No.  115550;  (3)  interior  of  another  right  valve,  X  1; 
U.  S.  Nat.  Mus.  No.  135665;  (4)  interior  of  small  left  valve,  X  1;  U.  S 
Nat.  Mus.  No.  115551;  page  155. 

Figs.  5  to  9.  Antigona  ( Ventricola )  blandiana  (Guppy).  (5)  Exterior  and  (6)  interior  of 
holotype  (right  valve),  X  1;  Dominican  Republic  (original  label  reads 
“Haiti”);  U.  S.  Nat.  Mus.  No.  115548;  (7)  exterior  of  right  valve,  X  1; 
U.  S.  Nat.  Mus.  No.  352833;  (8)  exterior  and  (9)  interior  of  small  right 
valve,  X  1;  (1  of  3  specimens  in  Guppy  collection  also  labeled  “types”); 
U.  S.  Nat.  Mus.  No.  115547;  page  157. 

Figs.  10,  11.  Cyclinella  plasia, tenuis,  n.  sp.  Holotype  (left  valve),  X  1.5;  (10)  exterior  and 

(11)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352834;  page  158. 
Figs.  12  to  14.  Chione  ( Chione )  sawkinsi,  n.  sp.  (12)  Exterior  of  right  valve  (1  of  7  speci¬ 
mens  in  Guppy  collection  labeled  “types”  of  Venus  woodwardi,  though 
the  actual  type  is  in  the  British  Museum),  X  1.5;  U.  S.  Nat.  Mus.  No. 
115545;  (13)  exterior  and  (14)  interior  of  holotype  (different  right  valve), 
X  1.5;  U.  S.  Nat.  Mus.  No.  352836;  page  159. 

PLATE  22. 

Figs.  1  to  4.  Chione  ( Chione )  woodwardi  (Guppy).  (1)  Exterior  and  (2)  interior  of  left 
valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  352836;  (3)  exterior  and  (4)  interior 
of  right  valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  135667;  page  160. 

Figs.  5,  6.  Chione  ( Chione )  retugida,  n.  sp.  Holotype  (left  valve),  X  4;  (5)  exterior  and 
(6)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352837;  page  161. 
Figs.  7  to  10.  Chione  ( Lirophora )  hendersoni  Dali.  (7)  Exterior  and  (8)  interior  of  cotype 
(right  valve),  X  1.5;  U.  S.  Nat.  Mus.  No.  115543;  (9)  interior  of  left 
valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  115542;  (10)  exterior  of  large  left 
valve,  X  1.5;  U.  S.  Nat.  Mus.  No.  352838;  page  163.  In  figure  8  the 
anterior  cardinal  is  broken. 

Figs.  11,  12.  Parastarte  antillensis,  n.  sp.  Holotype,  (left  valve),  X  8;  (11)  exterior  and 

(12)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352839;  page  164. 
Figs.  13  to  15.  Cooperella  (Cooper ellopsis)  thaumasta,  n.  sp.  Holotype  (left  valve),  X  4; 

(13)  exterior,  (14)  interior,  and  (15)  dorsal  views,  of  same  specimen; 
U.  S.  Nat.  Mus.  No.  352840;  page  165.  In  figure  13  the  shell  is  tilted  to 
the  left. 

PLATE  23. 

Figs.  1  to  3.  Tellina  (Moerella)  simpsoni  Dali.  (1)  Exterior  of  holotype  (right  valve),  X  4; 

U.  S.  Nat.  Mus.  No.  135697;  (2)  interior  of  different  right  valve,  X  4; 
U.  S.  Nat.  Mus.  No.  352841;  (3)  interior  of  small  left  valve,  X  4;  U.  S. 
Nat.  Mus.  No.  135697;  page  167.  In  figure  3  the  hinge  is  defective. 


220 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Figs.  4  to  7.  Tellina  { Moerella )  hendersoni  Dali.  (4)  Exterior  of  holotype  (left  valve), 
X  4;  U.  S.  Nat.  Mus.  No.  135696;  (5)  interior  of  different  left  valve,  X  4; 
U.  S.  Nat.  Mus.  No.  352842;  (6)  exterior  and  (7)  interior  of  right  valve, 
X  4;  U.  S.  Nat.  Mus.  No.  135696;  page  167. 

Figs.  8,  9.  Tellina  {Eurytellina)  species.  (8)  Exterior  and  (9)  interior  of  right  valve,  X  4; 
U.  S.  Nat.  Mus.  No.  135703;  page  168. 

Figs.  10,  11.  Tellina  { Eurytellina )  spiekeri ,  n.  sp.  Holotype  (right  valve),  X  4;  (10) 
exterior  and  (11)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352843; 
page  168. 

Figs.  12  to  15.  Tellina  { Eurytellina )  pharcida  Dali.  (12)  Exterior  of  holotype  (right  valve), 
X  4;  (13)  interior  of  another  right  valve,  X  4;  U.  S.  Nat.  Mus.  No.  135706; 
(14)  exterior  and  (15)  interior  of  left  valve,  X  4;  IT.  S.  Nat.  Mus.  No. 
353074;  page  169. 

Figs.  16,  17.  Tellina  ( Eurytellina )  gonida ,  n.  sp.  Holotype  (left  valve),  X  6;  (16)  exterior 
and  (17)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352844;  page  169. 

Fig.  18.  Tellina  { Eurytellina )  halistrepta  Dali.  Holotype  (right  valve),  X  2;  exterior; 
TJ.  S.  Nat.  Mus.  No.  135704;  page  169. 

Figs.  19,  20.  Tellina  {Eurytellina)  apomsa,  n.  sp.  Holotype  (right  valve),  X  6;  (19) 
exterior  and  (20)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352845; 
page  170. 

Figs.  21,  22.  Tellina  { Eurytellina )  browni,  n.  sp.  Holotype  (right  valve),  X  4;  (21) 
exterior  and  (22)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352846; 
page  170. 

PLATE  24. 

Figs.  1  to  4.  Tellina  { Merisca )  sclera  sclera  Dali.  (1)  Exterior  of  holotype  (right  valve), 
X  4;  (2)  interior  of  left  valve,  X  4;  U.  S.  Nat.  Mus.  No.  135698;  (3) 
exterior  and  (4)  interior  of  right  valve,  X  4;  U.  S.  Nat.  Mus.  No. 
352847;  page  171. 

Figs.  5,  6.  Tellina  { Merisca )  sclera  lerasca ,  n.  subsp.  Holotype  (left  valve),  X  4;  (5) 
exterior  and  (6)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352848; 
page  172. 

Figs.  7  to  10.  Tellina  { Merisca )  acrocosmia  Dali.  (7)  Exterior  and  (8)  interior  of  holotype 
(right  valve),  X  4;  (9)  exterior  and  (10)  interior  of  left  valve,  X  4;  U.  S. 
Nat.  Mus.  No.  135699;  page  172. 

Figs.  11  to  13.  Tellina  { Scissula )  healyi,  n.  name.  (11)  Exterior  of  holotype  (left  valve),  X  4; 

U.  S.  Nat.  Mus.  No.  135707;  (12)  exterior  and  (13)  interior  of  right  valve, 
X  4;  U.  S.  Nat.  Mus.  No.  352849;  page  173. 

Figs.  14  to  16.  Tellina  {. Elliptotellina )  cymobia,  n.  sp.  (14)  Exterior  and  (15)  interior  of 
holotype  (left  valve),  X  4;  U.  S.  Nat.  Mus.  No.  352850;  (16)  interior  of 
right  valve,  X  4;  U.  S.  Nat.  Mus.  No.  353075;  page  174. 

Figs.  17,  18.  Strigilla  {Strigilla)  pisiformis  Linne.  (17)  Exterior  and  (18)  interior  of  right 
valve,  X  4;  U.  S.  Nat.  Mus.  No.  352851;  page  175. 

Fig.  19.  Macoma  ( Psammocoma )  tracta  Dali.  Holotype  (right  valve),  X  4;  exterior;  U.  S. 
Nat.  Mus.  No.  135702;  page  176. 

Figs.  20,  21.  Macoma  { Psammacoma )  olivella  Dali.  Holotype  (left  valve),  X  2;  (20) 
exterior  and  (21)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  135708; 
page  177. 

Figs.  22  to  24.  Macoma  { Cymatoica )  vendryesi  Dali.  (22)  Exterior  of  cotype  (left  valve), 
X  4;  U.  S.  Nat.  Mus.  No.  135695;  (23)  exterior  and  (24)  interior  of  larger 
right  valve,  X  4;  U.  S.  Nat.  Mus.  No.  352852;  page  178. 

PLATE  25. 

Figs.  1,  2.  Semele  {Semele)  calliconcinnata,  n.  sp.  Holotype  (left  valve),  X  4;  (1)  exterior 
and  (2)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352853;  page  178. 

Figs.  3,  4.  Abra  { Abra )  triangulata  Dali.  (3)  exterior  and  (4)  interior  of  left  valve,  X  4; 
U.  S.  Nat.  Mus.  No.  352854;  page  179. 

Figs.  5,  6.  Abra  {Abra)  deutera,  n.  sp.  Holotype  (right  valve),  X  8;  (5)  exterior  and  (6) 
interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352855;  page  180. 

Figs.  7,  8.  Donax  {Donax)  species.  (7)  Exterior  and  (8)  interior  of  right  valve,  X  4; 
U.  S.  Nat.  Mus.  No.  135693;  page  181. 


DESCRIPTIONS  OF  PLATES. 


221 


Figs.  9,  10.  Donax  ( Paradonax )  lennoxi,  n.  sp.  Holotype  (left  valve),  X  4;  (9)  exterior 
and  (10)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  135693;  page  182. 

Figs.  11  to  14.  Psammosolen  sancti-dominici  Maury.  (11)  Exterior  and  (12)  interior  of 
left  valve,  X  1;  U.  S.  Nat.  Mus.  No.  352856;  (13)  exterior  and  (14) 
interior  of  larger  right  valve  (specimen  in  Henderson  collection  labeled 
“ Macha  vicksburgensis  Aid.?”)  X  1;  U.  S.  Nat.  Mus.  No.  135681;  page  182. 
In  figures  12  and  14  the  hinge  is  defective. 

Figs.  15,  16.  Spisula  ( Mactromeris )  matleyi,  n.  sp.  Holotype  (right  valve),  X  1.5;  (15) 
exterior  and  (16)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  352857; 
page  184. 

Figs.  17,  18.  Ervilia  gabbi,  n.  sp.  Holotype  (left  valve),  X  6;  (17)  exterior  and  (18)  interior 
of  same  specimen;  U.  S.  Nat.  Mus.  No.  352858;  page  185. 

Figs.  19  to  22.  Corbula  ( Corbula )  sericea  Dali.  (19)  Exterior  and  (20)  interior  of  right 
valve,  X  4;  (21)  exterior  and  (22)  interior  of  left  valve,  X  4;  U.  S.  Nat. 
Mus.  No.  352859;  page  186. 

PLATE  26. 

Figs.  1  to  4.  Corbula  ( Corbula )  heterogena  Dali.  (1)  Exterior  and  (2)  interior  of  holotype 
(right  valve),  X  2;  U.  S.  Nat.  Mus.  No.  107099;  (3)  exterior  and  (4) 
interior  of  left  valve,  X  2;  U.  S.  Nat.  Mus.  No.  352860;  page  187. 

Figs.  5  to  8.  Corbula  ( Bothrocobula )  viminea  Guppy.  (5)  Exterior  and  (6)  interior  of 
right  valve,  X  2;  (7)  exterior  and  (8)  interior  of  left  valve,  X  2;  (2  of  5 
specimens  in  Guppy  collection  labeled  “  types,”  though  the  actual  type 
is  in  the  British  Museum);  U.  S.  Nat.  Mus.  No.  115648;  page  189. 

Figs.  9,  10.  Basterotia  ( Basterotia )  bcwdeniana  Dali.  Holotype  (right  valve),  X  2;  (9) 
exterior  and  (10)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No.  135749; 
page  191. 

Figs.  11,  12.  Gastrochaena  ( Gastrochaena )  rotunda  Dali.  (11)  Exterior  and  (12)  interior  of 
left  valve,  X  2;  U.  S.  Nat.  Mus.  No.  352861;  page  192. 

Figs.  13  to  15.  Jouannetia  sphaeroidalis  (Guppy).  Holotype  (both  valves  originally  in 
attached  position),  X  4;  (13)  right  valve,  (14)  anterior  end,  and  (15) 
posterior  end  of  same  specimen;  U.  S.  Nat.  Mus.  No.  107100;  page  193. 

Figs.  16,  17.  Martesia  bowdeniana  (Dali).  Holotype  (anterior  part  of  left  valve),  X  4; 

(16)  exterior  and  (17)  interior  of  same  specimen;  U.  S.  Nat.  Mus.  No. 
135737;  page  194. 

Fig.  18.  Xylophaga?  species.  Exterior  of  imperfect  left  valve,  X  4;  U.  >S.  Nat.  Mus.  No. 
135738;  page  195. 

PLATE  27. 

Figs.  1,  2.  Dentalium  ( Dentalium )  cossmannianum  Pilsbry  and  Sharp.  (1)  Lateral  view 
and  (2)  section  of  anterior  end  of  broken  specimen,  X  4;  U.  S.  Nat.  Mus. 
No.  352713;  page  197. 

Figs.  3,  4.  Dentalium  ( Dentalium )  glaucoterrarum  Maury.  (3)  Lateral  view  and  (4)  section 
of  anterior  end  of  broken  specimen,  X  4;  U.  S.  Nat.  Mus.  No.  352714; 
page  198. 

Figs.  5,  6.  Dentalium  ( Dentalium ?)  species  o.  (5)  Lateral  view  and  (6)  section  of  anterior 
end  of  broken  specimen,  X  6;  U.  S.  Nat.  Mus.  No.  352715;  page  198. 

Figs.  7,  8.  Dentalium  ( Dentalium ?)  species  b.  (7)  Lateral  view,  X  6;  and  (8)  section  of 
anterior  end  of  broken  specimen,  X  12;  U.  S.  Nat.  Mus.  No.  352716; 
page  199. 

Figs.  9  to  14.  Dentalium  ( Tesseracme )  dissimile  dissimile  Guppy.  (9)  Lateral  view,  (10) 
section  of  posterior  end,  and  (11)  section  of  anterior  end  of  specimen  with 
broken  apex,  X  2;  U.  S.  Nat.  Mus.  No.  352717;  (12)  lateral  view,  (13) 
section  of  anterior  end,  and  (14)  section  of  posterior  end  of  large  specimen 
with  sculptured  posterior  part  broken  off,  X  2;  U.  S.  Nat.  Mus.  No. 
352718;  page  199. 

Figs.  15  to  17.  Dentalium  ( Tesseracme )  dissimile  ponderosum  Gabb.  (15)  Lateral  view,  (16) 
section  of  posterior  end,  and  (17)  section  of  anterior  end  of  specimen 
broken  at  both  ends,  X  2;  U.  S.  Nat.  Mus.  No.  352719;  page  200. 


222 


MIOCENE  MOLLUSKS  FROM  BOWDEN. 


Figs.  18  to  20.  Dentalium  ( Laevidentalium )  haytense  Gabb.  (18)  Lateral  view  of  large 
specimen  broken  at  both  ends,  X  4;  (19)  lateral  view  and  (20)  section  of 
anterior  end  of  small  specimen  broken  at  both  ends,  X  4;  U.  S.  Nat.  Mus. 
No.  352720;  page  202. 

Figs.  21  to  23.  Dentalium  ( Episiphon )  schumoi  Pilsbry.  (21)  Lateral  view  and  (22)  section 
of  anterior  end,  X  6;  (23)  apical  detail  of  same  specimen,  X  12;  U.  S.  Nat. 
Mus.  No.  352721;  page  203. 

Figs.  24,  25.  Dentalium  ( Episiphon )  macilentum  Pilsbry.  (24)  Lateral  view  and  (25) 
section  of  anterior  end  of  same  specimen,  X  6;  U.  S.  Nat.  Mus.  No. 
352722;  page  204. 


PLATE  28. 

Fig.  1.  Cadulus  ( Cadulus )  simrothi  Pilsbry.  Dorsal  view,  X  10;  U.  S.  Nat.  Mus.  No. 
352723;  page  205. 

Figs.  2,  3.  Cadulus  ( Gadilopsis )  dentalinus  (Guppy).  Cotype;  (2)  lateral  view,  X  4;  (3) 
lateral  view  of  apical  part,  X  8;  U.  S.  Nat.  Mus.  No.  115607;  page  206. 
Fig.  4.  Cadulus  ( Gadilopsis )  hendersoni ,  n.  sp.  Holotype,  X  4;  lateral  view;  U.  S.  Nat.  Mus. 
No.  352724;  page  207. 

Figs.  5,  6.  Cadulm  ( Polyschides )  annulatus  Pilsbry.  (5)  Lateral  view,  X  4;  (6)  detail  of 
sculpture,  X  8;  U.  S.  Nat.  Mus.  No.  135528;  page  207. 

Figs.  7  to  9.  Cadulus  ( Platyschides )  depressicolis  Pilsbry  and  Sharp.  (7)  Lateral,  (8) 
dorsal,  and  (9)  ventral  views  of  specimen  broken  at  posterior  end,  X  4; 
U.  S.  Nat.  Mus.  No.  352725;  page  209. 

Fig.  10.  Cadulus  ( Platyschides )  yilsbryi ,  n.  sp.  Holotype,  X  4;  lateral  view;  U.  S.  Nat. 
Mus.  No.  352726;  page  209. 

Fig.  11.  Cadulus  ( Platyschides )  annectens ,  n.  sp.  Holotype,  X  8;  lateral  view;  U.  S.  Nat. 
Mus.  No.  353077;  page  210. 

Fig.  12.  Cadulus  ( Platyschides )  arrosus,  n.  sp.  Holotype,  X  8;  lateral  view;  U.  S.  Nat. 
Mus.  No.  353078;  page  210. 


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WOODRING 


PLATE  1 


1.  Nucula  (Nucula)  morantensis  X  4. 

2,  3.  Nucula  (Nuculopsis)  hilli,  X  2. 

4,  5.  Leda  (Saecella)  peltella,  X  4. 

6,  7.  Leda  (Saecella)  subcerata,  X  4. 

S  to  10.  Leda  (Saecella)  indigena,  X  4. 

11,  12.  Leda  (Jupiteria)  bowdenensis  bowdenensis, 
X  4. 


13,  14.  Leda  (Jupiteria)  bowdenensis  subtumida, 
X  4. 

15,  16.  Leda  (Jupiteria)  duerdeni,  X  4. 

17  to  19.  Leda  (Pseudoportlandia)  clara,  X  4. 

20,  21.  Yoldia  (Orthoyoldia)  ovalis,  X  4. 

22,  23.  Tinclaria  (Tindaria)  sp.,  X  10. 


WOODRING 


PLATE  2 


1  to  3.  Glycymeris  (Glycymeris)  jamaicensis,  X 

1.5. 

4,  5.  Glycymeris  (Glycymeris)  acuticostata  pla- 
sia,  X  1.5. 


6,  7.  Glycymeris  (Glycymerella)  prepennacea, 
X  1.5. 

8,  9.  Area  (Area)  occidentals,  X  1. 

10,  11.  Area  (Area)  umbonata  morantensis,  X  1.5 


WOODRING 


PLATE  3 


1  to  4.  Area  (Area)  bowdeniana,  X  2. 

5,  6.  Area  (Area)  yaquensis  berryi,  X  2. 

7,  8.  Barbatia  (Barbatia)  islopa,  X  1.5. 

9,  10.  Barbatia  (Barbatia)  propertua,  X  3 
11,  12.  Barbatia  (Barbatia)  delepida,  X  3. 
13,  14.  Barbatia  (Barbatia)  endomena,  X  2 


15,  16.  Barbatia  (Barbatia)  inusitata,  X  1.5. 

17,  18.  Barbatia  (Acar)  domingensis,  X  1.5. 

19,  20.  Barbatia  (Obliquarca)  dentera,  X  1.5. 
21,  22.  Barbatia  (Obliquarea)  subeandida,  X  2 
23,  24.  Barbatia  (Obliquarca)  modiolida,  X  4. 


WOODRING 


PLATE  4 


1,  2.  Area  antiquata. 

3,  4.  Barbatia  (Diluvarca)  halidonata  halidonata, 


X  1. 


5,  6.  Barbatia  (Diluvarca)  halidonata  oresta,  X  1. 

7.  Barbatia  (Diluvarca)  perplura,  X  1.5. 

8.  Barbatia  (Diluvarca)  prephina,  X  1.5. 


WOODRING 


PLATE  5 


1  to  3.  Barbatia  (Diluvarca)  inaequilateralis,  X  1.5.  8  to  11.  Barbatia  (Diluvarca)  donacia,  X  4. 

4.  Barbatia  (Diluvarca)  dasia,  X  1.5.  12,  13.  Barbatia  (Diluvarca)  microtera,  X  4. 

5.  Barbatia  (Diluvarca)  wordeni,  X  1.5.  14,  15.  Barbatia  (Diluvarca)  ophthanta,  X  4. 

6.  Barbatia  (Diluvarca)  agnastha,  X  1.5.  16,17.  Fossularca  (Fossularca)  adamsi  sawkinsi,  X  2. 

7.  Barbatia  (Diluvarca)  thomasensis  X  2.  18  to  21.  Fossularca  (Ovalarca)  ovalina,  X  6. 


WOODRING 


PLATE  6 


1 


2 


1  to  3.  Bathyarca  hendersoni,  X  10. 

4  to  5.  Limopsis  (Pectunculina)  ovalis  silova,  X  4 
6,  7.  Limopsis  (Pectunculina)  jamaicensis,  X  10. 

8.  Pinna  refurca,  X  1.5. 


9.  Atrina  sp.,  X  1.5. 

10.  Isognomon  sp.,  X  1.5. 

11.  Pteria  inornata,  X  2. 

12  to  14.  Ostrea  (Lopha)  paramegodon,  X  1.5. 


WOODRING 


PLATE  7 


1,  2.  Ostrea  (Lopha)  guppyi,  X  1.5.  8,  9.  Pecten  (Euvola)  bowdenensis,  X  1. 

3  to  5.  Ostrea  (Lopha)  folioides,  X  1.5.  10.  Chlamys  (Chlamys)  sp.,  X  6. 

6,  7.  Pecten  (Pecten)  barretti,  X  1. 


WOODRING 


PLATE  8 


1,  2.  Chlamys  (Chlamys)  vaginulus,  X  3. 

3.  Chlamys  (Chlamys)  bellipictus,  X  6. 

4,  5.  Chlamys  (Aequipecten)  plurinominis  moran- 
tensis,  X  1. 

6,  7.  Chlamys  (Plagioctenium)  uselmae,  X  1. 


8.  Chlamys  (Plagioctenium)  concinnatus,  X  2. 

9.  Chlamys  (Plagioctenium)  ameleus,  X  2. 

10.  Chlamys  (Plagioctenium)  mansfieldi,  X  4. 

11,  12.  Chlamys  (Plagioctenium)  gonioides,  X  2. 
13  to  16.  Chlamys  (Palliolum?)  guppyi,  X  8. 


WOODRtNG 


PLATE  9 


1,  2.  Amusium  (Amusium)  papyraceum?  X  1, 
3,  4.  Amusium  (Parvamussium)  spendulum,  X 
5,  6.  Spondylus  bostrychites,  X  1. 

7.  Spondylus  bostrychites,  X  1.5. 


8.  Spondylus  sp.,  X  3. 

6.  9  to  11.  Plicatula  guppyi,  X  2. 

12,  13.  Lima  (Lima)  stenacostata,  X  4. 
14,  15.  Lima  (Mantellum)  sp.,  X  4. 


WOODRING 


PLATE  10 


1,  2.  Limea  solida,  X  8. 

3,  5.  Placunanomia  lithobleta,  X  1. 

6  to  9.  Anomia  indecisa,  X  2. 

10  to  12.  Modiolus  (Brachydontes)  guppyi,  X  4. 


13,  14.  Mytilopsis  jamaicensis,  X  2. 

15,  16.  Julia  gardnerae,  X  3. 

17  to  19.  Poromya  jamaicensis,  X  4. 

20  to  22.  Cuspidaria  (Cardiomya)  craspedonia,  X  6. 


. 


WOODRING 


PLATE  11 


1  to  5.  Cuspidaria  (Bowdenia)  distira,  X  6. 

6  to  8.  Verticordia  (Trigonulina)  bowdenensis, 
X  6. 

9  to  11.  Verticordia  (Haliris)  jamaicensis,  X  6. 


12  to  15.  Crassatellites  (Crassatellites) 


X  1. 

16,  17.  Crassatellites  (Crassatellites) 

X  1. 


jamaicensis 

altaspissus 


J 


7 


18  to  20.  Crassinelli  guppyi,  X  6. 


WOODRING 


PLATE  12 


1  to  4.  Crassinella  bowdenensis,  X  6. 

5,  6.  Crassinella  xena,  X  10. 

7  to  9.  Cardita  (Gians)  scabricostata,  X  2. 

10  to  12.  Venericardia  (Pleuromeris)  acaris,  X  6. 


13  to  16.  Chama  involuta,  X  2. 

17.  Chama  involuta,  X  6. 

18,  19.  Chama  macerophylla,  X  1.5. 


WOODRiNG 


PLATE  13 


f£x 


1  to  4.  Echinochama  antiquata,  X  1. 

5,  6.  Codakia  (Codakia)  spinulosa,  X  2. 
7,  8.  Codakia  (Codakia)  lomonea,  X  2. 


WOODRING 


PLATE  14 


1  to  4.  Codakia  (Jagonia)  vendryesi,  X  4. 
5  to  7.  Codakia  (Jagonia)  guppyi,  X  2. 
8,  9.  Lucina  (Lucina)  bowdenensis,  X  1.5. 


10  to  12.  Myrtaea  (Myrtaea)  limoniana,  X  2. 

13  to  16.  Myrtaea  (Myrtaeopsis)  pertenera,  X  1.5. 


WOODRING 


PLATE  15 


1  to  3.  Myrtaea  (Eulopia)  vermiculata,  X  4. 
4,  5.  Myrtaea  (Eulopia)  furcata,  X  2. 

6.  Miltha  (Megaxinus)  gluminda,  X  1.5. 

7.  Phacoides  (Phacoides?)  sp.,  X  1.5. 


8  to  11.  Phacoides  (Linga)  podagrinus  podagrinus, 

X  1.5. 

12.  Phacoides  (Linga)  podagrinus  alarantus, 

X  1. 


» 


i 


WOODRING 


PLATE  16 


1.  Phacoides  (Linga)  browni,  X  1. 

2,  3.  Phacoides  (Linga)  tithonis,  X  6. 

4  to  6.  Phacoides  (Pleurolucina)  quadricostatus, 
X  6. 

(,  8.  Phacoides  (Cardiolucina)  recurrens,  X  4. 


9  to  13.  Phacoides  (Callucina)  pauperatus  pauper¬ 
atus,  X  2. 

14,  15.  Phacoides  (Callucina)  pauperatus  oligocos- 
tatus,  X  2. 

16,  17.  Phacoides  (Callucina)  eurycostatus,  X  4. 


WOODRING 


PLATE  17 


1,  2.  Phacoides  (Parvilucina)  yaquensis  moranten- 
sis,  X  6. 

3,  4.  Phacoides  (Parvilucina)  limnidus,  X  6. 

5  to  8.  Phacoides  (Bellucina)  actinus,  X  6. 

9  to  13.  Divaricella  (Divaricella)  prevaricata,  X  2. 


14,  15.  Diplodonta  (Diplodonta)  walli,  X  6. 

16,  17.  Diplodonta  (Diplodonta)  homalostriata, 
X  6. 

18  to  21.  Diplodonta  (Felaniella)  minor,  X  6. 


WOODRING 


PLATE  18 


1  to  3.  Diplodonta  (Phlyctiderma)  gabbi,  X  6. 
4,  5.  Erycina  (Erycina)  olssoni,  X  6. 

6,  7.  Erycina  (Erycina)  pura,  X  6. 

8,  9.  Meaeromya  menotreta,  X  6. 


10,  11.  Cardium  (Acanthocardia?)  dissidepictum, 

X  1.5. 

12,  13.  Cardium  (Trachycardium)  lingualeonis,  X  1. 
14  to  16.  Cardium  (Trachycardium)  bowdenense, 
X  2. 


WOODRING 


PLATE  19 


1,  2.  Cardium  (Trachycardium)  inconspicuum,  X  1. 
3,  4.  Cardium  (Trachycardium)  waylandi,  X  1. 

5,  6.  Cardium  (Fragum)  medium,  X  1. 

7.  Cardium  (Fragum)  elattocostatum,  X  4. 

8,  9.  Cardium  (Trigoniocardia)  haitense  haitense, 
X  1.5. 


10,  11.  Cardium  (Trigoniocardia)  haitense  cerca- 
dicum,  X  1.5. 

12,  13.  Cardium  (Trigoniocardia)  thaumastum 
X  2. 

14  to  16.  Cardium  (Laevicardium)  serratum,  X  1. 
17.  Protocardia  (Nemocardium)  jamaicensis,  X  4. 


WOODRING 


PLATE  20 


MR ; 


1  to  5.  Pliocardia  bowdeniana,  X  4. 

6,  7.  Tivela  (Tivela)  jamaicensis,  X  4. 

8  to  10.  Gafrarium  (Gouldia)  insulare,  X  4. 


11,  12.  Callocardia  (Oallocardia)  ammondea,  X  4. 
13,  14.  Callocardia  (Callocardia)  elethusa,  X  4. 

15  to  19.  Pitar  (Hyphantosoma)  carbaseus,  X  1. 


WOODRING 


es&t&sgg 

.  ■  . .  Xx 


1  to  4.  Pitar  (Hysteroconcha)  planivietus,  X  1.  10,  11.  Cyclinella  plasiatenuis,  X  1.5. 

5  to  9.  Antigona  (Ventricola)  blandiana,  X  1.  12  to  14.  Chione  (Chione)  sawkinsi,  X  1.5. 


WOODRING 


PLATE  22 


1  to  4.  Chione  (Chione)  woodwardi,  X  1.5.  11,  12.  Parastarte  antillensis,  X  8. 

5,  6.  Chione  (Chione)  retugida,  X  4.  13  to  15.  Cooperella  (Cooperellopsis)  thaumasta, 

7  to  10.  Chione  (Lirophora)  hendersoni,  X  1.5.  X  4. 


WOODRING 


PLATE  23 


1  to  3.  Tellina  (Moerella)  simpsoni,  X  4. 

4  to  7.  Tellina  (Moerella)  hendersoni,  X  4. 

8,  9.  Tellina  (Eurytellina)  sp.,  X  4. 

10,  11.  Tellina  (Eurytellina)  spiekeri,  X  4. 
12  to  15.  Tellina  (Eurytellina)  pharcicla,  X  4. 


16,  17.  Tellina  (Eurytellina)  gonida,  X  6. 

18.  Tellina  (Eurytellina)  halistrepta,  X  2. 
19,  20.  Tellina  (Eurytellina)  apomsa,  X  6. 

21,  22.  Tellina  (Eurytellina)  browni,  X  4. 


WOODRING 


PLATE  24 


1  to  4.  Tellina  (Merisca)  sclera  sclera,  X  4. 

5,  6.  Tellina  (Merisca)  sclera  lerasca,  X  4. 

7  to  10.  Tellina  (Merisca)  acrocosmia,  X  4. 

11  to  13.  Tellina  (Scissula)  healyi,  X  4. 

14  to  16.  Tellina  (Elliptotellina)  cymobia,  X  4. 


17,  18.  Strigilia  (Strigilla)  pisiformis,  X  4. 

19.  Macoma  (Psammacoma)  tract.a,  X  4. 

20,  21.  Macoma  (Psammacoma)  olivella,  X  2. 

22  to  24.  Macoma  (Cymatoica)  vendryesi,  X  4. 


. 


J  Cn 


WOODRING 


PLATE  25 


1,  2.  Semelc  (Semele)  calliconcinnata,  X  4. 
3,  4.  Abra  (Abra)  triangulata,  X  4. 

,  6.  Abra  (Abra)  deutera,  X  8. 
i ,  8.  Donax  (Donax)  sp.,  X  4. 

9,  10.  Donax  (Paradonax)  lennoxi,  X  4. 


11  to  14.  Psamosolen  Sancti-dominici,  X  1. 

15,  16.  Spisula  (Mactromeris)  mateleyi,  X  1.5. 
17,  18.  Ervilla  gabbi,  X  6. 

19  to  22.  Corbula  (Corbula)  sericea,  X  4. 


M  IMMil 


WOODRING 


PLATE  26 


1 


13 


18 


16 


1  to  4.  Corbula  (Corbula)  heterogena,  X  2. 

5  to  8.  Corbula  (Bothrocorbula)  viminea,  X  2. 

9,  10.  Basterotia  (Basterotia)  bowdeniana,  X  2. 
11,  12.  Gastrochaena  (Gastrochaena)  rotunda,  X  2. 


13  to  15.  Jouannetia  sphaeroidalis,  X  4. 
16,  17.  Martesia  bowdeniana,  X  4. 

18.  Xylophaga?  sp.,  X  4. 


t 


PLATE  27 


21  22  25  24 

15  to  17.  Dentalium  (Tesseracme)  dissimile  ponde- 
rosum,  X  2. 

18  to  20.  Dentalium  (Laevidentalium)  hay  tense 
X  4. 

21,  22.  Dentalium  (Episiphon)  schumoi,  X  6. 

23.  Dentalium  (Episiphon)  schumoi,  X  12. 

24,  25.  Dentalium  (Episiphon)  macilentum,  X  0. 


1,  2.  Dentalium  (Dentalium)  cossmannianum,  X  4. 
3,  4.  Dentalium  (Dentalium)  glaucoterrarum,  X  4. 
5,  6.  Dentalium  (Dentalium?)  sp.  a,  X  6. 

7.  Dentalium  (Dentalium?)  sp.  b.,  X  6. 

8  Dentalium  (Dentalium?)  sp.  b,  X  12. 

9  to  14.  Dentalium  (Tesseracme)  dissimile  dis¬ 
simile,  X  2. 


WOODRING 


PLATE  28 


1.  Cadulus  (Cadulus)  simrothi,  X  10. 

2.  Cadulus  (Gadilopsis)  dentalinus,  X  4. 

3.  Cadulus  (Gadilopsis)  dentalinus,  X  8. 

4.  Cadulus  (Gadilopsis)  hendersoni,  X  4. 

5.  Cadulus  (Polyschides)  annulatus,  X  4. 


6.  Cadulus  (Polyschides)  annulatus,  X  8. 

7  to  9.  Cadulus  (Platyschides)  depressicolis,  X  4. 

10.  Cadulus  (Platyschides)  pilsbryi,  X  4. 

11.  Cadulus  (Platyschides)  annectens,  X  8. 

12.  Cadulus  (Platyschides)  arossus,  X  8. 


1HE  UBRAM 


